Exfoliation of a layered high-T_c superconductor

层状高温超导体的剥离

基本信息

批准号：
11640331
负责人：
SHAMOTO Shin-ichi
金额：
$ 2.24万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11640331/
关键词：
superconductor layered nitride exfoliation inorganic monolayer

项目摘要

In the present research, exfoliation of a layered high-T_c superconductor Li_x (THF)_yHfNCl has been studied, where organic solvents such as pyridine, dimethylsulfoxide, N,N-dimethylformamide, and N-methylformamide were used to solve the Li_x(THF)_yHfNCl sample with large interlayer distance, i.e., about 1.87 nm. Unfortunately, our Li_x(THF)_yHfNCl sample (x〜0.5) has never been dissolved in these solvents. On the other hand, structures and physical properties on related honeycomb lattice superconductors, such as Na_<0.29>HfNCl and Li_<0.19>ZrNBr, have also been studied. Structures of related superconductors, Na_<0.29>HfNCl and Li_<0.19>ZrNBr, have been determined successfully by Rietveld analysis using neutron diffraction data. We are the only research group that has succeeded in determining the structures of these alkali metal intercalated superconducting samples, which are unstable in air. Inelastic neutron scattering study of Na_xHfNCl revealed that the phonon density of states (PDOS) at several energies much higher than the superconducting energy gap increased remarkably, which was the similar behavior to high-T_c cuprates, e.g., La_<1.85>Sr_<0.15>CuO_4 and YBa_2Cu_3O_7. Recent neutron scattering studies indicate that these increases of PDOS relating to phonon dispersion anomaly would be due to the existence of dynamical charge density wave (DCDW). It suggests that DCDW might be a common characteristic among high-T_c superconductors with some electronic instability including Ba_<1-x>K_xBiO_3, which seems to be quite different with one another in terms of spin fluctuation.

本研究采用吡啶、二甲基亚砜、N,N-二甲基甲酰胺、N-甲基甲酰胺等有机溶剂溶解Li_x(THF)_yHfNCl，研究了层状高温超导体Li_x(THF)_yHfNCl的剥离。 _yHfNCl 样品具有较大的层间距离，即约 1.87 nm 不幸的是，我们的。 Li_x(THF)_yHfNCl样品(x〜0.5)从未溶解在这些溶剂中。另一方面，Na_<0.29>HfNCl和Li_<0.19>ZrNBr等相关蜂窝晶格超导体的结构和物理性质也发生了变化。研究了相关超导体Na_<0.29>HfNCl和的结构。 Li_<0.19>ZrNBr，已通过中子衍射数据通过Rietveld分析成功确定，我们是唯一成功确定这些碱金属插层超导样品结构的研究小组，这些样品在空气中不稳定。 Na_xHfNCl揭示了在远高于超导能隙的几个能量下声子态密度（PDOS）显着增加，这与高T_c铜酸盐，例如La_<1.85>Sr_<0.15>CuO_4和YBa_2Cu_3O_7。最近的中子散射研究表明，与声子色散异常相关的PDOS的增加可能是由于动态电荷密度波（DCDW）的存在。表明 DCDW 可能是具有一些电子不稳定性的高温超导体的共同特征，包括Ba_<1-x>K_xBiO_3，在自旋波动方面似乎彼此有很大不同。