2009 Fiscal Year Final Research Report
Investigations of electronic properties of novel anisotropic superconductors with light-mass ions by scanning tunneling microscopy/spectroscopy
| Project/Area Number |
19540370
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Condensed matter physics II
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| Research Institution | Hiroshima University |
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Principal Investigator |
EKINO Toshikazu Hiroshima University, 大学院・総合科学研究科, 教授 (40185103)
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| Project Period (FY) |
2007 – 2009
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| Keywords | 層状窒化物超伝導体 / トンネル分光 / 走査トンネル顕微鏡分光(STM / STS) / 超伝導ギャップ |
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| Research Abstract |
We have investigated the layered nitride superconductors by means of the low-temperature ultra-high vacuum scanning tunneling microscopy/spectroscopy (STM/STS). The STM topographies at 5K clearly indicate the difference in the surface arrangements of metal atoms between α(FeOCl) and β(SmSI) layered polymorphs. The STS spectra exhibit a large difference between them. For α-K_xTiNCl, the energy gap 2Δ is very inhomogeneous down to the area of ～20nm^2, while for β-HfNCl_<0.7> they are homogeneous even up to ～100nm^2. The maximum gap ratio 2Δ/k_BT_c (k_B : Boltzmann constant, Tc : critical temperature) ～40 for α-K_xTiNCl and the uniform ratio 2Δ/k_BTc～10 for β-HfNCl_<0.7> are both larger than the BCS value 3.5, thereby indicating that the pairing mechanism is different from that of the conventional superconductors.
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