Toshikazu Ekino

Last Updated :2021/04/06

Affiliations, Positions
Graduate School of Advanced Science and Engineering, Professor
Web Site
E-mail
ekinohiroshima-u.ac.jp

Basic Information

Academic Degrees

  • Doctor of Science, Aoyama Gakuin University
  • Master of Science, Aoyama Gakuin University

Educational Activity

  • 【Bachelor Degree Program】School of Integrated Arts and Sciences : Department of Integrated Arts and Sciences
  • 【Master's Program】Graduate School of Advanced Science and Engineering : Division of Advanced Science and Engineering : Quantum Matter Program
  • 【Master's Program】Graduate School of Advanced Science and Engineering : Division of Advanced Science and Engineering : Transdisciplinary Science and Engineering Program
  • 【Doctoral Program】Graduate School of Advanced Science and Engineering : Division of Advanced Science and Engineering : Quantum Matter Program
  • 【Doctoral Program】Graduate School of Advanced Science and Engineering : Division of Advanced Science and Engineering : Transdisciplinary Science and Engineering Program

In Charge of Primary Major Programs

  • Integrated Arts and Sciences

Research Fields

  • Mathematical and physical sciences;Physics;Condensed matter physics II

Research Keywords

  • superconductivity
  • nanoscale science
  • energy gap
  • Break junction tunneling
  • STM/STS
  • Tunnelling
  • electronic properties of cuprate superconductors
  • iron-based high-Tc superconductivity
  • electronic properties of f-electron system

Educational Activity

Course in Charge

  1. 2021, Liberal Arts Education Program1, 1Term, Experimental Methods and Laboratory Work in Physics I
  2. 2021, Liberal Arts Education Program1, 2Term, Experimental Methods and Laboratory Work in Physics II
  3. 2021, Liberal Arts Education Program1, 3Term, Fundamental PhysicsI
  4. 2021, Liberal Arts Education Program1, First Semester, Introduction to Physics
  5. 2021, Liberal Arts Education Program1, 1Term, Introductory Seminar for First-Year Students
  6. 2021, Undergraduate Education, 1Term, Introduction to Physical Sciences
  7. 2021, Undergraduate Education, 3Term, Electromagnetism II
  8. 2021, Undergraduate Education, 1Term, Laboratory Work in Material Sciences C
  9. 2021, Undergraduate Education, 1Term, Experimental Methods for Materials Sciencs C
  10. 2021, Graduate Education (Master's Program) , Academic Year, Special Study of Advanced Science and Engineering Transdisciplinary Science and Engineering
  11. 2021, Graduate Education (Master's Program) , First Semester, Special Exercises of Advanced Science and Engineering Transdisciplinary Science and Engineering A
  12. 2021, Graduate Education (Master's Program) , Second Semester, Special Exercises of Advanced Science and Engineering Transdisciplinary Science and Engineering B
  13. 2021, Graduate Education (Master's Program) , 3Term, Spectroscopies of Correlated Matter

Research Activities

Academic Papers

  1. Tunneling spectra of break junctions involving Nb3Sn, LOW TEMPERATURE PHYSICS, 40(10), 925-928, 201410
  2. Dynamics and mechanism of oxygen annealing in Fe1+yTe0.6Se0.4 single crystal, SCIENTIFIC REPORTS, 4, 20140403
  3. Variable electronic stripe structures of the parent iron-chalcogenide superconductor Fe1+dTe observed by STM-STS, PHYSICAL REVIEW B, 90(22), 20141202
  4. Scanning-tunneling microscopy and break-junction spectroscopy on the superconducting Fe(Se, Te) single crystal, PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS, 484, 22-26, 201301
  5. ★, Tunneling break-junction measurements of the superconducting gap in Y2C3, PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS, 484, 52-55, 201301
  6. ★, STM/STS and break-junction tunneling spectroscopy of FeSe1-xTex, LOW TEMPERATURE PHYSICS, 39(3), 265-273, 201303
  7. Superconducting beta-ZrNClx probed by scanning-tunnelling and break-junction spectroscopy, PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS, 494, 89-94, 201311
  8. Nanoscale electronic structure of the layered nitride superconductors alpha-KxTiNCl and beta-HfNCly observed by scanning tunneling microscopy and spectroscopy, PHYSICAL REVIEW B, 85(14), 20120417
  9. Specific heat and Tunneling Spectroscopy study of NbB2 with maximum T-c similar to 10K, JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 76(9), 200709
  10. Break-junction measurements of CeNiSn under magnetic fields, Physica B, 230, 635, 19970401
  11. Observation of the Energy Gar above Tc in (Bi, Pb)2Sr2Ca2Cu2O10+d Using Break Junction Tunneling, Journal of Low Tempereture Physics, 117(3-4), 359, 19990401
  12. Break Junctionでみた高温超伝導体Bi2Sr2CaCu2O8+8dのTc以上でのギャップ構造, 72(4), 436, 19990401
  13. Superconducting energy gap of La1.85Sr0.15CuO4 single crystals from break-junction tunneling, Physica C, 263, 249, 19960401
  14. Energy gap in Lu-substituted YbB12 proved by break junction, Physica B, 281&282, 278-279, 20000801
  15. Tunneling Spectroscopy of the Kondo-semiconducting gap in YbB12, Physica B, 259-261, 315-316, 19990801
  16. Electron-Tunneling Studies of the Cubic Kondo Semiconductors, Japanese Journal of Applied Physics, series 11, 97-99, 19990801
  17. Giant Magnetoresistance in Ce2Fe17, Physical Review B, 56, 13716-13719, 19970401
  18. Substitution effect on the unstable ferromagnet CeFe2, Physica B, 281&282, 92-93, 20000401
  19. Hydrogen Absorption in La2-xSrxCuO4 with Mono-Layer CuO6 Octahedra., Physica B, 165-166, 1529-1530, 19900401
  20. Carrier Localization in Hydrogen-Doped La1.9A1.1Cu2O6+y (A = Ca, Sr)., Supercond. Sci. Technol., 4, S208-210, 19910401
  21. Feasibility of Electron Donation to the CuO2 Plane of Mono-layer Copper by Hydrogen Absorption., Physica C, 185-189, 845-846, 19910401
  22. Latttice Instabilities and Superconductivity in La2-x(Ba,Sr)xCuO4., Springer Proc. in Phys. 60 The Physics and Chemistry of Oxide Superconductors eds Y. Iye and H.Yasuoka= Springer-Verlag Berlin= Heidelberg, Phys. 60, 201-204, 19920401
  23. Hydrogenation Effects on Copper-Oxide Superconductors,, Special Issue of JJAP= Mechanism of Superconductivity 1992. Jpn. J. Appl. Phys., 7, 34-40, 19920401
  24. Effect of Hydrogenation on YBa2Cu3O0.9 and Bi2Sr2CaCu2O8.2., Physica B, 194-196, 1941-1942, 19940401
  25. Interaction of Hydrogen with YBa2Cu3O6.9, Bi2Sr2CaCu2O8.2 and La1.9Ca1.1Cu2O6 Ceramics., 6, 399-402, 19940401
  26. Superconducting Energy Gap in Quaternary Intermetallic Compound YNi2B2C., Physica C, 235-240, 2529-2530, 19940401
  27. Superconducting energy gaps in YBa2Cu3O7 and Bi2Sr2CaCu2O8., Physica C, 235-240, 1899-1900, 19940401
  28. Tunneling Measurements of the Energy Gap in CeRhSb and CeNiSn, Physica B, 206-207, 837-839, 19950401
  29. Tunnelling spectroscopy of superconducting energy gap in RNi2B2C (R=Y and Lu), Phy. Rev. B 53, 53, 5640-5649, 19960401
  30. Tunneling Spectroscopy of CeRhSb Single Crystal, Physica B, 223-224, 444-446, 19960401
  31. Tunneling measurements of the superconducting gap in CeRu2, Czecho. J. Phys. 46 (1996)= Suppl. S2= p. 783-784., 46, Suppl. S2, p. 783-784, 19960401
  32. Electron tunneling into superconducting CeRu2, Phys. Rev. B, 56, 7851-7854, 19970401
  33. Tunneling Spectroscopy of the Kondo semiconductor Ce3Bi4Pt3, J. MAG. MAG. MAT., 177-181, 379-380, 19980401
  34. Tunneling Spectroscopy of Bi2Sr2CuO6+y under Mahnetic Fields. Advaces in Superconductivity X, Proc. of the 10th Inter. Sympo. on Superconductivity= Springer - Verlag Tokyo, 10, 183-186, 19980401
  35. Anomalous Magnetic and Transport Properties in Ce2Fe17 and Lu2Fe17, J. Magn. Soc. Japan 23 (1999) 108-110., 23, 108-110, 19990401
  36. Gap Measurements of the Antiferromagnetic Compound Ce2Fe17, J. Magn. Soc. Japan, 23, 111-113, 19990401
  37. Magnetic-field Dependence of the Energy Gap in Bi2Sr2CuO6, Advance in Superconductivity XI= Proc. of the 11th Inter. Sympo. On Superconductivity= Fukuoka= 1998= Springer-Verlag= 1999., 11, 169-172, 19990401
  38. Break-junction Measurements of the Energy Gap above Tc in Bi2Sr2CaCu2O8+, Advance in Superconductivity XI= Proc. of the 11th Inter. Sympo. On Superconductivity= Fukuoka= 1998= Springer-Verlag= 1999., 11, 177-180, 19990401
  39. Break-Junction Spectroscopy of Ce(Fe,Co)2 Physica B 284-288 (2000) 1327-1328., Physica B, 284-288, 1327-1328, 20000401
  40. Probing the normal-state gap in high-Tc superconductors by break-junction tunneling, J. Phys. and Chem. Solids, 62, 149-152, 20010401
  41. Tunneling spectroscopy of the energy gap in semiconducting La1.98Sr0.02CuO4, Physica C, 357-360, 158-161, 20010401
  42. Tunneling spectroscopy of the nornal-state gap in (Bi,Pb)2Sr2Ca2Cu3O10+d, Phys. Rev. B, 64, 092510-1 to 4, 20010401
  43. Synthesize of the binary intermetallic superconductor MgB2 under hydrogen pressure, J. Alloys and Compounds, 335, L21-L24, 20020401
  44. Energy gap in the Kondo semiconductor CeRhAs, Physica B, 312-313, 221-223, 20020401
  45. Superconducting gap in polycrystalline MgB2 stdied by electron tunneling, Physica C, 378-381, 229-233, 20020401
  46. Tunneling spectroscopy of MgB2 and Li0.5(THF)yHfNCl, Physica B, 328, 23-25, 20030401
  47. Tunneling spectroscopy of the electron-doped layered superconductor Li0.48(THF)0.3HfNCl, Physica C, 388-389, 573-574, 20030401
  48. Multiple-gap structure of the binary superconductor MgB2, Physica C, 388-389, 147-148, 20030401
  49. Tunneling spectroscopy of the superconducting gap in MgB2., Phys. Rev. B, 67, 094504-1 to 6, 20030401
  50. Possible application of carbon nanotubes to the field emission electron source for portable betatrons, Nucl.Instr.and Meth.in Phys.Res.=B109/110, A539, 16-24, 20050401
  51. Break-junction tunneling spectra of MgB2 Influence of boron quality, Physica C, 426-431, 450-453, 20050401
  52. Spin-dependent tunneling in a magnetic field for junctions involving normal and superconducting CDW metals, Acta Physica Polonica A, 109, 477-484, 20060401
  53. Tunneling spectroscopy of AlB2 type silicide CaAlSi, Physica B, 383, 80-81, 20060401
  54. Tunneling spectroscopy of single-crystal clathrate Ba8Ga16Sn30, Physica B, 383, 126-127, 20060401
  55. Electron tunneling experiments on La-substituted Kondo semiconductor CeRhAs, Physica B, 383, 26-27, 20060401
  56. Tunneling spectroscopy of the electron-doped superconductors MNCl0.7 (M= Hf, Zr), Physica C, 445-448, 77-79, 20060401
  57. Spin dependent tunneling current in junctions involving CDW metals, Jpn. J. Appl. Phys., 45, 2242-2245, 20060401
  58. Spin dependent splitting of the tunnel conductivity peaks in the magnetic field for junctions involving CDW metals, Physica B, 378-380, 567-568, 20060401
  59. Tunneling measurements of CeRhAs single crystal, Physica B, 378-380, 786-787, 20060401
  60. Current carrier localization and coulomb gap observed in SrPbO3-エ by transport measurements and tunnel spectroscopy, Physica B: Condensed Matter, 17, 7407-7416, 20050401
  61. Tunneling spectroscopy of deintercalated layered nitride superconductors ZrNCl0.7, J. Phys. Soc. Japan, 74, 2586-2591, 20050401
  62. Manifestations of inhomogeneity in MgB2: From specific heat to tunnel measurements, Physica B, 359-361, 460-462, 20050401
  63. Enhancement of the paramagnetic limit for superconductors with charge-density waves, Physica C, 426-431, 325-329, 20050401
  64. Point-contact spectroscopy measurements of binary superconductor MgB2, Physica C, 426-431, 300-303, 20050401
  65. Electrical resistivity and tunneling anomalies in CeCuAs2, Physica B, 359-361, 108-110, 20050401
  66. Spin-polarized electron tunneling between charge-density-wave metals, Low Temp. Phys., 31, 59-72, 20050401
  67. Pauli effect of the magnetic field on superconductors with charge-density waves, Low Temp. Phys., 31, 41-46, 20050401
  68. Superconducting energy gap from break-junction tunneling spectroscopy in the ternary silicide CaAlSi, Phys. Rev. B, 76(10), 104508-(1-5), 20070901
  69. Charge-Density-Wave origin of Dip-Hump Structures in the Tunnel Spectra of Bi2Sr2CaCu2O8+d, Acta Physica Polonica A, 111(4), 573-580, 20070401
  70. Evidence for the Fine Pseudogap at the Fermi Level in Al-based Quasicrystals, Journal of the Physical Society of Japan, 76(3), 033707-(1-4), 20070301
  71. Analysis of the pseudogap-related structure in tunneling spectra of superconducting Bi2Sr2CaCu2O8+d revealed by the break-junction technique, Physical Review B, 76(18), 180503-(1-4), 20071101
  72. Scanning tunnelling microscopy and spectroscopy of MgB2, Joural of Physics: Conference Series, 61, 278-282, 20070501
  73. Observation of local barrier height and electronic structure on cuprate superconductor by STM/STS, Journal of Physics Conference Series, 100, 052003/1-4, 20080301
  74. Nanoscale Modulation of Local Barrier Height on Bi-based Cuprate Superconductors Observed by Scanning Tunneling Microscopy/Spectroscopy, Journal of the Physical Society of Japan, 77, 043705/1-4, 20080401
  75. STM Observation on Layered Nitride Superconductor KxTiNCl, Journal of Physics: Conference Series, 150, 052251/1-4, 20090401
  76. Scanning Tunneling Microscopy/Spectroscopy on Multi-Layered Cuprate Superconductor Ba2Ca5Cu6O12(O1-xFx)2, Physica C, 469, 1020-1023, 20090601
  77. Semiconducting gap of Nd1.85Ce0.15CuO4 revealed by break junction tunneling spectroscopy, Journal of Physics: Conference Series, 150, 052046/1-4, 20090401
  78. Temperature-dependent pseudogap-like features in tunnel spectra of high-Tc cuprates as a manifestation of charge-density waves, Journal of Physics: Condensed Matter, 20, 425218/1-15, 20080501
  79. Pseudogap-like phenomena in cuprates as a manifestation of charge-density waves, Acta Physica Polonica A, 114, 59-66, 20080601
  80. Observation of local barrier height and electronic structure on cuprate superconductor by STM/STS, Journal of Physics: Conference Series, 100, 052003/1-4, 20080501
  81. Tunnel spectra of junctions involving BSCCO and other cuprates: superconducting and charge-density-wave gapping, Physica C, 468, 1145-1147, 20080601
  82. Charge-density-wave features in tunnel spectra of high-Tc superconductors, Journal of Physics: Conference Series, 150, 052047/1-4, 20090401
  83. Tunneling spectroscopy of layered superconductors : intercalated Li0.48(C4H8O)xHfNCl and De-intercalated HfNCl0.7, The European Physical Journal B, 73, 471-482, 20100201
  84. Scanning Tunneling Spectroscopy and Break Junction Spectroscopy on Iron-Oxypnictide Superconductor NdFeAs(O0.9 F0.1), Physica C, 470, 1070-1072, 20101101
  85. Atomic-scale spot structures and gap distributions on apical-fluorine cuprate superconductor Ba2Ca5Cu6O12 (O 1-x Fx)2 observed by STM/STS, Physica C, 470, S160-S162, 20101101
  86. Tunneling Break-Junction Spectroscopy on the Superconductor NdFeAs(O0.9F0.1), Physica C, 470, S358-S359, 20101101
  87. Atomic surface structures on multi-layered cuprate superconductor Ba2Ca4Cu5O10(O1-x Fx)2 observed by STM, 471, 698-700, 20111001
  88. Scanning tunneling microscopy on iron-chalcogenide superconductor Fe(Se,Te) single crystal, Physica C, 471, 622-624, 20111101
  89. Competition of superconductivity and charge-density-waves in cuprates: recent evidence and interpretation, Advances in Condensed Matter Physics, 2010, 681070(1-40), 20101001
  90. STM/STS Observation on Layered Nitride Superconductor alpha-(DDA)xTiNCl, Journal of Physics: Conference Series, 400, 022112/1-4, 20121201
  91. Phase diagram for coexisting d-wave superconductivity and charge-density-waves; cuprates and beyond, Journal of Physics: Condensed Matter, 23, 385701(1-22), 20110401
  92. d-Wave Superconductivity and s-Wave Charge Density Waves: Coexistence between Order Parameters of Different Origin and Symmetry, Symmetry, 3, 1-47, 20110301
  93. Nano-scale stripe structures on FeTe observed by low temperature STM/STS, Physics Procedia, 45, 85-88, 20130501
  94. Anisotropic transport and magnetic properties and magnetic-polaron-like behavior in CeTe2-x, JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 69(3), 937-944, 200003
  95. Tunneling spectroscopy of RTe2 (R = La, Ce) and possible coexistence between charge-density waves and magnetic order, PHYSICAL REVIEW B, 63(3), 20010115
  96. Magnetic and transport properties or the pseudobinary systems Ce(Fe1-xCox)(2) and (Ce1-ySc)Fe-2, PHYSICAL REVIEW B, 63(5), 20010201
  97. Observation of a pseudogap in alpha-AlMnSi by break-junction tunneling spectroscopy, JOURNAL OF NON-CRYSTALLINE SOLIDS, 312-14, 513-516, 2002
  98. Tunneling spectroscopy of MgB2 and Li-0.5(THF)(y)HfNCl, PHYSICA B-CONDENSED MATTER, 328(1-2), 23-25, 200304
  99. Tunneling spectroscopy of the superconducting gap in MgB2, PHYSICAL REVIEW B, 67(9), 20030301
  100. Tunneling measurements of superconducting NbB2, PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS, 408, 828-829, 200408
  101. Formation of midgap states and ferromagnetism in semiconducting CaB6, PHYSICAL REVIEW B, 69(11), 200403
  102. Enhanced paramagnetic limit of the upper critical magnetic field for superconductors with charge-density waves, JOURNAL OF PHYSICS-CONDENSED MATTER, 16(21), 3681-3690, 20040602
  103. Multiple-gap features from break-junction tunneling in the superconducting MgB2, JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 73(7), 1902-1913, 200407
  104. Tunnel currents in charge-density-wave metal-insulator-charge-density-wave metal structures: Magnetic field-induced spin-splitting of the conductance peaks, JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 73(7), 1931-1937, 200407
  105. Energy gap structure in the binary superconductor MB2 (M = Nb and Mg), PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS, 412, 266-269, 200410
  106. Paramagnetic effect of magnetic field on superconductors with charge-density waves, LOW TEMPERATURE PHYSICS, 31(1), 41-46, 200501
  107. Spatially heterogeneous character of superconductivity in MgB2 as revealed by local probe and bulk measurements, PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS, 426, 230-233, 20051001
  108. Tunneling spectroscopy of layered nitride superconductors MNCl0.7 (M = Hf and Zr), PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS, 445, 77-79, 20061001
  109. Evidence of the fine pseudogap at the fermi level in Al-based quasicrystals, JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 76(3), 200703
  110. Tunneling Evidence for the Quasiparticle Gap in Kondo Semiconductors CeNiSn and CeRhSb, Physical Review Letters, 75(23), 4262-4265, 19951204
  111. Observation of the gap distribution on multi-layered cuprate superconductor Ba2Ca4Cu5O10(O1-x, Fx)2 by STM/STS, Physics Procedia, 58, 78-81, 20140923
  112. Break junction tunneling spectroscopy of superconducting FeSexTe1-x, Physics Procedia, 65, 65-68, 2015
  113. Tunneling STM/STS and break-junction spectroscopy of the layered nitro-chloride superconductors MNCl (M = Ti, Hf, Zr), Journal of Physics Conference Series, 507, 012010-1-012010-5, 2014
  114. Spatially inhomogeneous superconductivity in MgB2, First International Conference: Fundamental Problems of High-Tc superconductivity-FPS-04 (2004)
  115. Electron tunneling into superconducting CeRu2, Physical Review B, 56, 7851-7854, 1997
  116. Neutron scattering study of antiferromagnetic correlations in CeNi1-xCoxSn, Physica B, 223-224, 432-434, 1996
  117. Vacuum-tunneling spectroscopy of heavy-fermion compounds using a low-temperature tunnelling microscope, Czech. J. Phys., 46, 797-798, 1996
  118. Neutron scattering study of antiferromagnetic correlations in the Kondo semiconductor CeNiSn, Journal of Physics Condensed Matter, 7, 8009-8026, 1995
  119. Feature of the energy gap in YBa2Cu3O7 from break junction measurements, HIGH-TC SUPERCONDUCTIVITY AND TUNNELING PHENOMENA, National Academy of Sciences of Ukraine, 25-28, 1995
  120. Combined break-junction tunneling and STM/STS studies of the β-tungsten-type superconductor Nb3Sn below and above Tc, Journal of Energy Challenges and Mechanics, 1-6
  121. The spatial distributions of large gap-like structure on Fe(Se,Te) single crystals observed by STM/STS, PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS, 518, 23-27, 20151115
  122. Hybridization gaps and antiferromagnetic gap in the Kondo semiconductors CeT2Al10 (T = Fe and Os) observed by break- junction tunneling spectroscopy, PHYSICAL REVIEW B, 92(20), 20151124
  123. Combined break-junction tunneling and STM/STS studies of the beta-tungsten-type superconductor Nb3Sn below and above Tc, Journal of Energy Challenges and Mechanics, 2, 138-142, 2015
  124. Influence of the spatially inhomogeneous gap distribution on the quasiparticle current in c-axis junctions involving d-wave superconductors with charge density waves, JOURNAL OF PHYSICS-CONDENSED MATTER, 28(44), 445701_1-445701_10, 20161109
  125. ★, Doping effects on the hybridization gap and antiferromagnetic order in the Kondo semiconductor CeOs2Al10 studied by break-junction experiments, PHYSICAL REVIEW B, 95(3), 20170115
  126. ★, Multilayered cuprate superconductor Ba$_2$Ca$_5$Cu$_6$O$_{12}$(O$_{1-x}$,F$_x$)$_2$ studied by temperature dependent scanning tunneling microscopy and spectroscopy, Physical Review B, 95, 174508_1-174508_11, 20170516
  127. Scanning Tunneling Microscopy and Spectroscopy of the Layered Nitride Superconductor a-NaxTiNCl, Physics Procedia, 81, 73-76, 2016
  128. Interplay between hybridization gaps and antiferromagnetic gap in the hole-doped Kondo semiconductor Ce(Os1-yRey)2Al10, Journal of Physics; Conference Series, 807, 012008_1-012008_6, 2017
  129. ★, Gap features of layered iron-selenium-tellurium compound below and above the superconducting transition temperature by break-junction spectroscopy combined with STS, IOP Conference Series: Materials Science and Engineering, 012024-1-012024-7, 20180725
  130. ★, STM/STS and break-junction study of multi-layered Ba2Can-1CunO2n(O,F)2(n=5,6) and underdoped Bi2Sr2CaCu2O8+d superconductors with the similar Tc~70 K, J. Energy Challenges and Mechanics, 5(1), 1-16, 201807
  131. Interplay between hybridisation gaps and unusual magnetic orders in Kondo semiconductors CeT2Al10 (T = Ru and Os), PHILOSOPHICAL MAGAZINE, 99(23), 2984-2999, 20191202
  132. Atomic structures and nanoscale electronic states on the surface of MgB2 superconductor observed by scanning tunneling microscopy and spectroscopy, LOW TEMPERATURE PHYSICS, 45(11), 1209-1217, 20191127
  133. Break-junction tunneling spectra of Bi2212 superconducting ceramics: Influence of inhomogeneous d-wave-Cooper-pairing and charge-density-wave order parameters, LOW TEMPERATURE PHYSICS, 46(4), 400-413, 202004
  134. d-Wave superconductivity and s-Wave charge density waves: Coexistence between order parameters of different origin and symmetry, Symmetry, 3(4), 699-749, 20111201
  135. Specific heat and Tunneling Spectroscopy study of NbB2 with maximum T-c similar to 10K, JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 76(9), 2007
  136. Nanoscale modulation of local barrier height on Bi-based cuprate superconductors observed by scanning tunneling microscopy/spectroscopy, JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 77(4), 2008
  137. Tunneling break-junction spectroscopy on the superconductor NdFeAs(O 0.9F0.1), Physica C: Superconductivity and its Applications, 470(SUPPL.1), S358-S359, 20101201
  138. STM/STS measurements of the layered superconductor β-HfNCl 1-x, Physica C: Superconductivity and its Applications, 470(SUPPL.1), S725-S727, 20101201
  139. The phase diagram for coexisting d-wave superconductivity and charge-density waves: cuprates and beyond, JOURNAL OF PHYSICS-CONDENSED MATTER, 23(38), 2011
  140. Nanoscale electronic structure of the layered nitride superconductors alpha-KxTiNCl and beta-HfNCly observed by scanning tunneling microscopy and spectroscopy, PHYSICAL REVIEW B, 85(14), 2012
  141. Scanning-tunneling microscopy and break-junction spectroscopy on the superconducting Fe(Se, Te) single crystal, Physica C: Superconductivity and its Applications, 484, 22-26, 20130115
  142. Superconducting β-ZrNClx probed by scanning-tunnelling and break-junction spectroscopy, Physica C: Superconductivity and its Applications, 494, 89-94, 20130624
  143. Dynamics and mechanism of oxygen annealing in Fe1+yTe0.6Se0.4 single crystal, SCIENTIFIC REPORTS, 4, 2014
  144. Tunneling spectra of break junctions involving Nb3Sn, Fizika Nizkikh Temperatur, 40(10), 1182-1186, 20140101
  145. Variable electronic stripe structures of the parent iron-chalcogenide superconductor Fe1+dTe observed by STM-STS, PHYSICAL REVIEW B, 90(22), 2014
  146. The spatial distributions of large gap-like structure on Fe(Se,Te) single crystals observed by STM/STS, PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS, 518, 23-27, 2015
  147. Multilayered cuprate superconductor Ba2Ca5Cu6O12(O1-x,F-x)(2) studied by temperature-dependent scanning tunneling microscopy and spectroscopy, PHYSICAL REVIEW B, 95(17), 2017
  148. Interplay between hybridisation gaps and unusual magnetic orders in Kondo semiconductors CeT2Al10 (T = Ru and Os), PHILOSOPHICAL MAGAZINE, 99(23), 2984-2999, 2019
  149. Atomic structures and nanoscale electronic states on the surface of MgB2 superconductor observed by scanning tunneling microscopy and spectroscopy, LOW TEMPERATURE PHYSICS, 45(11), 1209-1217, 2019
  150. Nano-scale periodic structures and gap distribution in Pb-doped Bi2223 cuprate superconductors observed by STM/STS, SUPERCONDUCTOR SCIENCE & TECHNOLOGY, 33(9), 2020
  151. Tunneling spectroscopy of layered superconductors: Intercalated Li 0.48(C 4H 8O) xHfNCl and De-intercalated HfNCl 0.7, European Physical Journal B, 73(4), 471-482, 20100201
  152. Analysis of the pseudogap-related structure in the tunnel spectra of superconducting Bi2Sr2CaCu2O 8+δ revealed by break-junction technique, Low Temperature Physics, 34(6), 409-412, 20080101
  153. Scanning tunnelling microscopy and spectroscopy of MgB2, Journal of Physics: Conference Series, 61(1), 278-282, 20070401
  154. Tunneling spectroscopy of layered nitride superconductors MNCl0.7 (M = Hf and Zr), Physica C: Superconductivity and its Applications, 445-448(1-2), 77-79, 20061001
  155. Tunneling spectroscopy of AlB2 type silicide superconductor CaAlSi, Physica B: Condensed Matter, 383(1), 80-81, 20060815
  156. Electron tunneling experiments on La-substituted Kondo-semiconductor CeRhAs, Physica B: Condensed Matter, 383(1), 26-27, 20060815
  157. Spin-dependent tunnel currents in junctions involving charge-density-wave metals, Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers, 45(3 B), 2242-2245, 20060327
  158. Current carrier localization and Coulomb gap observed in SrPbO 3-δ by transport measurements and tunnel spectroscopy, Journal of Physics Condensed Matter, 17(46), 7407-7416, 20051123
  159. Enhancement of the paramagnetic limit for superconductors with charge-density waves, Physica C: Superconductivity and its Applications, 426-431(I), 325-329, 20051001
  160. Point-contact spectroscopy measurements of binary superconductor MgB 2, Physica C: Superconductivity and its Applications, 426-431(I), 300-303, 20051001
  161. Spatially heterogeneous character of superconductivity in MgB2 as revealed by local probe and bulk measurements, Physica C: Superconductivity and its Applications, 426-431(I), 230-233, 20051001
  162. Tunneling spectroscopy of deintercalated layered nitride superconductor ZrNCl0.7, Journal of the Physical Society of Japan, 74(9), 2586-2591, 20050901
  163. Manifestations of inhomogeneity in MgB2: From specific heat to tunnel measurements, Physica B: Condensed Matter, 359-361(SPEC. ISS.), 460-462, 20050430
  164. Energy gap structure in the binary superconductor M B2 ( M = Nb and Mg), Physica C: Superconductivity and its Applications, 412-414(SPEC. ISS.), 266-269, 20041001
  165. Tunneling measurements of superconducting NbB2, Physica C: Superconductivity and its Applications, 408-410(1-4), 828-829, 20040801
  166. Multiple-gap features from break-junction tunneling in the superconducting MgB2, Journal of the Physical Society of Japan, 73(7), 1902-1913, 20040701
  167. Tunneling spectroscopy of the electron-doped layered superconductor Li0.48(THF)0.3HfNCl, Physica C: Superconductivity and its Applications, 388-389, 573-574, 20030501
  168. Multiple-gap structure of the binary superconductor MgB2, Physica C: Superconductivity and its Applications, 388-389, 147-148, 20030501
  169. Tunneling spectroscopy of MgB2 and Li0.5(THF)yHfNCl, Physica B: Condensed Matter, 328(1-2), 23-25, 20030401
  170. Semiconducting gap of Nd1.85Ce0.15CuO4 revealed by break-junction tunnelling spectroscopy, Journal of Physics: Conference Series, 150(5), 20090101
  171. Tunneling spectroscopy of the superconducting gap in MgB2, Physical Review B - Condensed Matter and Materials Physics, 67(9), 945041-945046, 20030301
  172. Superconducting gap in polycrystalline MgB2 studied by electron tunneling, Physica C: Superconductivity and its Applications, 378-381(PART 1), 229-233, 20021001
  173. Energy gap in the Kondo semiconductor CeRhAs, Physica B: Condensed Matter, 312-313, 221-223, 20020301
  174. Tunneling spectroscopy of various underdoped Bi2Sr2CaCu2O8+δ, Physica C: Superconductivity and its Applications, 357-360, 130-133, 20010101
  175. Probing the normal-state gap in high-Tc superconductors by break-junction tunneling, Journal of Physics and Chemistry of Solids, 62(1-2), 149-152, 20010101
  176. Tunneling spectroscopy of the energy gap in semiconducting La1.98Sr0.02CuO4, Physica C: Superconductivity and its Applications, 357-360, 158-161, 20010101
  177. Energy gap in Lu-substituted YbB12 probed by break junction, Physica B: Condensed Matter, 281-282, 278-279, 20000601
  178. Break-junction spectroscopy of antiferromagnetic Ce(Fe,Co)2, Physica B: Condensed Matter, 284-288(PART II), 1327-1328, 20000101
  179. Charge-density-wav features in tunnel spectra of high-T superconductors, Metrology and Measurement Systems, 15(2), 145-151, 20081201
  180. Features of the energy gap above Tcin Bi2Sr2CaCu2O8+δas seen by break-junction tunneling, Physical Review B - Condensed Matter and Materials Physics, 60(9), 6916-6922, 19990101
  181. Tunneling spectroscopy of the Kondo semiconductor Ce3Bi4Pt3, Journal of Magnetism and Magnetic Materials, 177-181(PART 1), 379-380, 19980101
  182. Scanning tunneling microscopy on iron-chalcogenide superconductor Fe(Se, Te) single crystal, Physica C: Superconductivity and its Applications, 471(21-22), 622-624, 20111101
  183. Superconducting energy gap of La1.85Sr0.15CuO4 single crystals from break-junction tunneling, Physica C: Superconductivity and its Applications, 263(1-4), 249-252, 19960101
  184. Competition of superconductivity and charge density waves in cuprates: Recent evidence and interpretation, Advances in Condensed Matter Physics, 2010, 20101201
  185. Scanning-tunneling microscopy/spectroscopy and break-junction tunneling spectroscopy of FeSe1-xTex, Low Temperature Physics, 39(3), 265-273, 20130327
  186. Tunneling break-junction measurements of the superconducting gap in Y 2C3, Physica C: Superconductivity and its Applications, 484, 52-55, 20130115
  187. Tunneling spectroscopy of Novel Layered superconductors: MgB2, Li0.48(THF)XHfNCl and related substances, Superconductivity: Theory, Materials and Applications, 1-110, 20120301
  188. Tunneling STM/STS and break-junction spectroscopy of the layered nitro-chloride superconductors MNCl (M Ti, Hf, Zr), Journal of Physics: Conference Series, 507(PART 1), 20140101
  189. Break-junction Tunneling Spectroscopy of Superconducting FeSexTe1-x, Physics Procedia, 65, 65-68, 20150101
  190. Tunneling spectroscopy of the superconducting gap in (formula presented), Physical Review B - Condensed Matter and Materials Physics, 67(9), 20030314
  191. Gap features of layered iron-selenium-tellurium compound below and above the superconducting transition temperature by break-junction spectroscopy combined with STS, IOP Conference Series: Materials Science and Engineering, 369(1), 20180612
  192. Tunneling spectroscopy of the Kondo-semiconducting gap in YbB12, Physica B: Condensed Matter, 259-261, 315-316, 19990101
  193. Tunneling measurements of as grown Bi2Sr2CaCu2O8+δ single crystals, Physica B: Condensed Matter, 259-261, 555-556, 19990101

Publications such as books

  1. 2007/10, Superconductivity Research Advances, Editor: James E. Nolan, COMPETITION BETWEEN SUPERCONDUCTIVITY AND CHARGE CARRIER LOCALIZATION IN PLUMBATES, NOVA SCIENCE PUBLISHERS, INC., 2007, 10, Scholarly Book, Joint work, ENGLISH, A.M. Gabovich, V.A. Drozd, M. Pekala, T. Ekino, R. Ribeiro,, 978600216916, 55
  2. 2012/03, Superconductivity: Theory, Materials and Applications, ed. by V.R. Romanovskií, The discovery of novel high-Tc superconductivity in MgB2 (Tc = 39.5 K) and Li0.48(THF)yHfNCl (Tc = 25.5 K) initiated substantial progress in the field of superconductivity physics and its applications despite the fact that competing high-Tc cuprates remain the world leaders in almost all practically important superconducting parameters. This article describes electron tunneling and point-contact experimental studies of the indicated two materials and related substances, being crucial to elucidate the character of the quasiparticle energy spectrum both in superconducting and normal state. The account is based mostly on our own experiments, although works carried out in other laboratories are taken into account as well. We studied superconducting gap structures by means of break-junction tunneling spectroscopy (BJTS), scanning tunneling spectroscopy (STS) and point-contact spectroscopy (PCS)., he discovery of novel high-Tc superconductivity in MgB2 (Tc = 39.5 K) and Li0.48(THF)yHfNCl (Tc = 25.5 K) initiated substantial progress in the field of superconductivity physics and its applications despite the fact that competing high-Tc cuprates remain the world leaders in almost all practically important superconducting parameters. This article describes electron tunneling and point-contact experimental studies of the indicated two materials and related substances, being crucial to elucidate the character of the quasiparticle energy spectrum both in superconducting and normal state. The account is based mostly on our own experiments, although works carried out in other laboratories are taken into account as well. We studied superconducting gap structures by means of break-junction tunneling spectroscopy (BJTS), scanning tunneling spectroscopy (STS) and point-contact spectroscopy (PCS)., Tunneling Spectroscopy of Novel Layered Superconductors: MgB2, Li0.48(THF)xHfNCl and Related Substances, Nova Science Publishers, Inc. New York, 2012, 03, Scholarly Book, Joint work, 9781613248430, 110
  3. 2015/08/01, SUPERCONDUCTORS NEW DEVELOPMENTS, Ed. A.M. Gabovich, Gap Structures of A-15 Alloys from the Superconducting and Normal-State Break-Junction Tunnelling pp.55-72, superconductor, A15, tunneling spectroscopy, energy gap, INTECH, 2015, Scholarly Book, Joint work, Toshikazu EKINO, Alexander M. GABOVICH, Akira SUGIMOTO, Yuta SAKAI, Jun AKIMITSU, 978-953-51-2133-6, 270, 22

Invited Lecture, Oral Presentation, Poster Presentation

  1. STM/STS and break junction tunneling spectroscopy of Fe(X(= Se,S), Te), T. Ekino, International Conference on Nanoscience and Technlogy (ICNT2012), Paris-Sorbonne University, 2012 July 21-27., 2012/07/26, Without Invitation, English
  2. 鉄カルコゲナイド超伝導体及びその母物質における局所状態密度の変調構造(2), 杉本暁,浴野稔一, 日本物理学会 第68回年次大会, 2013/03/29, Without Invitation, Japanese
  3. Superconducting gap of b-HfNCl and related compounds investigated by scanning tunneling microscopy / spectroscopy and break-junction tunneling, T. EKINO, International Conference on Nanoscience and Nanotechnology, 2013/09/12, Without Invitation, English, PARIS
  4. Tunneling STM/STS and break junction spectroscopy of the layered superconductors b-MNClx (M = H for Zr), T. EKINO, European Conference on Applied Superconductivity, 2013/09/19, Without Invitation, English, GENOVA
  5. STM/STSによる頂点フッ素系多層超伝導体Ba2Ca4Cu5(O,F)xにおけるギャップ分布観測, 杉本暁, 田中勝大, 峰田恭平, 田辺健治, 常磐和靖, 浴野稔一, 日本物理学会秋季大会, 2013/09/26, Without Invitation, Japanese, 日本物理学会, 徳島市
  6. STM/STS and break junction tunneling spectroscopy of the layered nitro-chloride superconductors, T. EKINO, International workshop on Novel superconductors and super materials, 2013/11/22, Without Invitation, English
  7. 層状窒化物超伝導体NaxTiNClのSTM/STS観測, 坂井優太, 杉本暁, S. Zhang, 田中将嗣, H. Zhu, 山中昭司, 浴野稔一, 日本物理学会年次大会, 2014/03/27, Without Invitation, Japanese, 日本物理学会, 平塚市
  8. STS/STM of the layered iron-chalcogenide and nitro-chloride superconductors, T. EKINO, AnalytiX-2014, 2014/04/28, Without Invitation, English
  9. STM/STSを用いた鉄カルコゲナイド鉄カルコゲナイド超伝導体FeSexTe1-xの局所障壁高さとトンネルスペクトルの観測, 杉本暁, 坂井優太, 浴野稔一, 日本物理学会年次大会, 2014/03/27, Without Invitation, Japanese
  10. 層状窒化物超伝導体NaxTiNClの電子状態密度の観測, 坂井優太, 杉本暁, S. Zhang, 田中将嗣, H. Zhu, 山中昭司, 浴野稔一, 日本物理学会秋季大会, 2014/09/09, Without Invitation, Japanese
  11. Suppression of hybridization gap and antiferromagnetic order by electron- and hole- doping in the Kondo Semiconductor CeOs2Al10, J. KawabataA, Y. YamadaA, K. UmeoA,B, T. TakabatakeA,C, Y. MuroD, SCES2014, 2014/07/07, Without Invitation, English
  12. STM/STSによる鉄カルコゲナイド超伝導体FeSexTe1-xにおける過剰鉄スポット形状と電子状態の観測, 杉本暁, 坂井優太, 浴野稔一, 日本物理学会秋季大会, 2014/09/09, Without Invitation, Japanese
  13. トンネル分光による近藤半導体CeT2Al10(T = Fe, Os)の擬ギャップ構造の観測, 川端丈A,山田義大A,高畠敏郎A,B,坂井優太C,杉本暁C,浴野稔一C, 日本物理学会 2014年秋季大会, 2014/09/09, Without Invitation, Japanese
  14. The spatial distributions of large pseudo gap on Fe(Se, Te) single crystals observed by STM/STS, A. SUGMOTO, T. EKINO, et al., International Symposium on Superconductivity (ISS2014), 2014/11/27, Without Invitation, English, Tokyo
  15. Break junction tunneling spectroscopy of superconducting FeSexTe1-x (x= 0.4-0.5) with our STM/STS result, T. EKINO, International Symposium on Superconductivity (ISS2014), 2014/11/27, Without Invitation, English, TOKYO
  16. 破断接合法トンネル分光による近藤半導体CeT2Al10(T = Fe, Os)のギャップ構造の観測, 川端丈A,山田義大A,高畠敏郎A,B,坂井優太C,杉本暁C,浴野稔一C,室裕司D, 日本物理学会 第70回年次大会, 2015/03/23, Without Invitation, Japanese
  17. Break Junction Tunneling Spectroscopy of Kondo Semiconductors CeT2Al10(T = Fe, OS), J. Kawabata, Y. Yamada, T. Takabatake, Y. Sakai, A. Sugimoto, T, Ekino, Y. Muro, ICM2015, 2015/07/07, Without Invitation, English
  18. Tunnelling measurements of Nb3Sn break junctions below and above the superconducting critical temperature, T. EKINO, Fourth International Symposium on Energy Challenges and Mechanics - working on small scales, 2015/08/13, With Invitation, English, North Sea Conference & Journal, Aberdeen, SCOTLAND, UK
  19. STM/STSを用いた鉄カルコゲナイド超伝導体母物質FeTeにおける周期的変調構造のバイアス電圧依存性, 杉本 暁*, 長坂 康平, 浴野 稔一, 日本物理学会秋季大会, 2015/09/16, Without Invitation, Japanese
  20. 破断接合法トンネル分光で観測した近藤半導体CeOs2Al10の5d電子・正孔ドープによるギャップ構造の抑制, 川端丈A, 山田義大A, 高畠敏郎A, B, 坂井優太C, 杉本暁C, 浴野稔一C, 室裕司D, 日本物理学会 2015年秋季, 2015/09/17, Without Invitation, Japanese
  21. 鉄セレン系超伝導体のトンネル分光 によるエネルギーギャップの測定, 長坂 康平, 杉本 暁, 浴野 稔一, 日本物理学会秋季大会, 2015/09/19, Without Invitation, Japanese
  22. Scanning Tunnelling Microscopy and Spectroscopy on the Layered Nitride Superconductor α-NaxTiNCl, Akira Sugimoto , Yuta Sakai, Toshikazu Ekino, Shuai Zhang, Masashi Tanaka, Shoji Yamanaka, A. M. Gabovich, 28th International Symposium on Superconductivity, ISS 2015, 2015/11/18, Without Invitation, English
  23. COMBINED STUDY OF THE ENERGY GAP IN FeSexTe1-x SUPERCONDUCTOR BY BREAK-JUNCTION AND SCANNING TUNNELING SPECTROSCOPY, EKINO TOSHIKAZU, The 5th annual conference of AnalytiX 2017, 2017/03/24, With Invitation, English, ANALYTIX, FUKUOKA, Single crystals of FeSexTe1-x superconductors were investigated by scanning tunneling microscopy/spectroscopy (STM/STS). We mainly focus on the compositions x = 0.4 – 0.5 showing the superconducting critical temperature Tc = 15 K. The BJTS method revealed a BCS-like gap structure with the values 2Δ (T ≈ 4 K) = 2.5 – 7 meV and the broadening parameter Γ < 0.1 Δ. The observed wide gap distribution can be due to either the local electronic inhomogeneity or the manifestations of the gaps from different Fermi surfaces. The largest normalized gap value becomes 2Δ/kBTc ≈ 5. From the STS measurements, the gap value 2Δ = 20 – 40 meV is detected locally in the superconducting state, which turns out to be much larger than that observed in the BJTS. Such a gap shape tends to appear at the excess Fe atoms in nm regions on the surface of iron-chalcogenide layer. In the high-bias BJTS, the samples with x = 0.4 – 0.5 demonstrate V-shape gaps at T ≈ 4 K with the peak intervals eVp-p = 4Σ = 80 – 160 meV. This hump structure forms the normal-state gap above Tc. Such behaviour is similar to the partially gapped density-wave superconductor involving both superconducting gap and pseudogap, which has been adapted to high-Tc cuprates [2]. Since the normal-state gap survives up to T* ≈ 60 – 100 K, the normalized gap value 2Σ/kBT* becomes ~ 9 - 13. Most probably, the normal-state gap is induced by charge-density waves, for which 2Σ/kBT* is anomalously high, as was observed for the quasi one-dimensional compounds [5]. These results suggest that the present normal-state gap is generated by the partial Fermi surface instability inherent to the low-dimensional electronic structures. The possible origins are discussed in terms of the local phase transition reducing the crystal symmetry due to strains and inhomogeneity. The mesurements of FeSe and non-superconducting FeTe will be also presented and discussed. [2] A.M. Gabovich, A.I. Voitenko, et al., Adv. Condens. Matter Phys. 2010, 681070 (2010). [3] T. Ekino, J. Akimitsu, Jpn. J. Appl. Phys. 26, 625 (1987).
  24. STM/STS study of the multi-layered flourine-substituted high-Tc superconductor Ba2Can-1CunO2n (O,F)2 (F02(n-1)n) (n=5,6), EKINO Toshikazu, 7th international symposium on energy, 2017/08/15, With Invitation, Japanese, North sea conference and journal, Manchester, We present the scanning tunneling microscopy and spectroscopy measurements of the multilayered apical fluorine Ba2Can-1CunO2n(O1-x,Fx)2 compound in order to elucidate the pseudogap problem. The family of materials studied here is suitable for the systematic investigation because of (i) the high enough Tc> 100 K, obtained by controlling the number of CuO2 layers, and (ii) the clean and flat cleaved surface of the BaO/F layers. The latter property makes it possible to study the intrinsic surface nanoscale inhomogeneity, which may be related to the high-Tc superconductivity per se or competing phenomena, contrary to the wide gap distributions observed in the Bi-based cuprates, which might be severely influenced by the structural factors.
  25. Combined study of FeSexTe1-x by break junction and scanning tunneling spectroscopy -Mutual comparison of BJTS and STS spectra-, EKINO Toshikazu, SUGIMOTO Akira, Alexander GABOVICH, IBS 2016 Advances in preparation and investigation of emergent Iron-Based Superconductors, 2016/05/23, With Invitation, English, Leibniz Institute for Solid State and Materials Research Dresden B.Verkin Institute for Low Temperature Physics and Engineering, Dresden, Germany, We investigated the energy gap in FeSexTe1-x single crystal with the bulk superconducting critical temperature Tc = 15 K, which is considerably higher than that for the pure FeSe. The measurements were carried out in a wide temperature range below and above Tc by the break-junction tunneling spectroscopy (BJTS) to maintain a fresh and unaffected surfaces. The scanning tunneling microscopy/spectroscopy (STM/STS) technique was also employed to survey the complementary density-of-states data. The BJTS method dealing with SIS (superconductor - insulator - superconductor) junctions revealed a Bardeen-Cooper-Schrieffer-like gap structure with the values 2Δ (T ≈ 4 K) = 2.5 – 7 meV and the broadening parameter not less than 0.1 Δ [1]. The wide gap distribution was detected, which is believed to originate either form the local electron spectrum inhomogeneity or from the manifestations of the gap belonging to different Fermi surfaces [2]. The largest gap value from the distribution corresponds to 2Δ/kBTc ≈ 5 being similar to our BJTS results for NdFeAsOF with Tc = 48 K and suggesting the same kind of the strong-coupling Cooper pairing [3]. Besides the conventional superconducting gap features, the high-bias BJTS demonstrates a V-shape gap structure at T ≈ 4 K with the peaks at ± 40 – 80 mV. In some measurements, those features may also appear as humps outside the superconducting-gap peak in a manner similar to the observations in high-Tc cuprates [4]. STM/STS measurements show that such a V-gap appears at the excess Fe atoms on the surface of iron-chalcogenide layer, clustering in nm regions. Since the V-gap structure survives up to T* ≈ 60 – 100 K, the gap-to-T* ratio is in the range 8 – 13. This characteristic value shows that the high-energy gaps are not connected to superconductivity with the corresponding smaller gaps discussed above. Most probably, larger (normal-state) gaps are induced by charge density waves, for which the ratio between the energy gap at zero T to the critical temperature is anomalously high, as was demonstrated many years ago for the quasi one-dimensional conductors [5]. Those results suggest that the normal-state gap observed here is generated by the electron spectrum instability leading to the partial Fermi surface gapping, inherent to the low-dimensional electronic structures. The possible specific origin is discussed in terms of the structural/magnetic phase transition locally reducing the crystal symmetry of FeSexTe1-x, the distribution of T* being naturally understood as driven by the existence of local strains and inhomogeneity. [1] T. Ekino, K. Nagasaka, Y. Sakai, A. Sugimoto, A.M. Gabovich, Physics Procedia 65, 65(2015). [2] H. Miao, P. Richard, Y. Tanaka, et al., Phys. Rev. B 85, 094506 (2012). [3] T. Ekino, A. Sugimoto, H. Okabe, K. Shohara, R. Ukita, et al., Physica C 470, S358 (2010). [4] A.M. Gabovich, A.I. Voitenko, et al., Adv. Condens. Matter Phys. 2010, 681070 (2010). [5] T. Ekino, J. Akimitsu, Jpn. J. Appl. Phys. 26, 625 (1987).
  26. Gap features of layered iron-selenium-tellurium compound below and above the superconducting transition temperature by break-junction spectroscopy combined with STS, Toshikazu EKINO, A Sugimoto and A M Gabovich, PCM 2018 2018 Grobal Conference on Polymer and composite Materials, 2018/04/11, With Invitation, English, Global Conference on Polymer and Composite Materials, Kitakyushu

Social Activities

Organizing Academic Conferences, etc.

  1. 2002/08

History as Peer Reviews of Academic Papers

  1. 2013, Solid State Communications, Others, 1
  2. 2013, SUPERCONDUCTOR SCIENCE AND TECHNOLOGY, Others, Reviewer, 2
  3. 2013, Current Opinion in Solid State & Materials Science, Others, Reviewer, 1
  4. 2013, Physical Review Letters, Others, Reviewer, 3
  5. 2013, Semiconductor Science and Technology, Others, Reviewer, 1
  6. 2014, Semiconductor Science and Technology, Others, Reviewer, 1
  7. 2014, Measurement Science and Technology, Others, Reviewer, 1
  8. 2014, Physical Review B, Others, Reviewer, 3
  9. 2014, Superconductor Science and Technology, Others, Reviewer, 1
  10. 2014, Journal of Physics Condensed Matter, Others, Reviewer, 2
  11. 2014, Applied Surface Science, Others, Reviewer, 1
  12. 2015, Applied Surface Science, Others, Reviewer, 1
  13. 2015, aterials Chemistry and Physics, Others, Reviewer, 1
  14. 2015, Solid State Communications, Others, Reviewer, 1
  15. 2015, Superconductor Science and Technology, REviewer, 1
  16. 2015, Physica C, Others, Reviewer, 1
  17. 2015, Journal of the Physical Society of Japan, Others, Reviewer, 1
  18. 2015, Physical Review B, Others, Reviewer, 1
  19. 2015, Journal of Physics Condensed Matter, Others, Reviewer, 1
  20. 2015, Journal of Physics D: Applied Physics, Others, Reviewer, 1
  21. 2016, Journal of Physics:Condensed Matter, Others, Reviewer, 1
  22. 2016, Scientific Reports, Others, Reviewer, 2
  23. 2016, Physical Review Letters, Others, Reviewer, 1
  24. 2017, Physical Review Letters, Others, Reviewer, 2
  25. 2017, New Journal of Physics, Others, Reviewer, 1
  26. 2017, Physical Review B, Others, Reviewer, 1
  27. 2017, Scientific Reports, Others, referee, 1
  28. 2017, Nanotechnology, Others, Referee, 1
  29. 2018, Journal of Physics: Condensed Matter, Others, Referee, 1
  30. 2018, Superconductor Science and Technlogy, Others, Referee, 1
  31. 2018, Physical Review Letters, Others, Referee, 1
  32. 2019, Journal of Physics Condensed Matter, Others, reviewer, 1
  33. 2019, Journal of Physcis Communications, Others, reviewer, 1
  34. 2019, Physical Review Letters, Others, Reviewer, 1
  35. 2019, Physical Review B, Others, Reviewer, 1
  36. 2019, International Journal of the Physical Sciences, Others, Reviewer, 1