Development and Application of Layer Structured Nitride Superconductors

层状结构氮化物超导体的开发与应用

基本信息

批准号：
14350461
负责人：
YAMANAKA Shoji
金额：
$ 9.6万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

We have reported that layer structured nitride halides β-MNX (M = Zr, Hf ; X = Cl, Br, I) electron-doped by intercalation of alkali metals became superconductors. In particular, the compound cointercalated with Li and THF (tetrahydrofuran), Lio_<48>(THF)_yHfNCl, showed a high critical temperature of Tc = 25.5 K. In this study, we have collaborated with solid state physicists to investigate the superconducting mechanism, and new types of layer structured nitrides have been developed. The main results obtained are the followings;1. Single crystals of β-MNX were successfully prepared using ammonium halides as fluxes under high-pressure conditions, and their structures were determined by the single crystal X-ray analysis.2. A new electron-doping method was developed by partial deintercalation of chlorine atoms to form β-ZrNCl_<1-x> and β-HfNCl_<1-x>, which were stable in air for pretty long time. The deintercalated samples showed similar superconductivity with those electron doped by alkali metal intercalation.3. Isotope substituted β-Hf^<15>NCl was prepared, and its superconductors were derived by electron doping.4. ^<15>N NMR study revealed that the layer structured nitride superconductors were two-dimensional ones with very low carrier densities and weak phonon enhancement. The mechanism of the new superconductors cannot be interpreted in the conventional BCS theory.5. The superconducting gap was successfully measured by a break-junction method.6. Layer structured Sr_2N oriented films were prepared by MBE method in a high vacuum chamber with a nitrogen radical source.

我们已经报道了层结构化的氮化卤化物β-MNX（M = Zr，Hf; X = Cl，Br，I）通过碱金属插入的电子掺杂变成了超导体。特别是，该化合物与Li和Thf（四氢呋喃）相关，LIO_ <48>（THF）_YHFNCL显示出TC = 25.5 K的较高临界温度。在这项研究中，我们与固态物理学家合作，与固体物理学家合作，以研究超管制机制，并开发了新型的层结构Nitrides nitrides nitrides nitries已开发。获得的主要结果是以下； 1。 β-MNX的单晶体使用卤化铵作为在高压条件下的通量成功制备，并通过单晶X射线分析确定其结构。2。通过部分去氯原子的部分去解剖来形成β-zrncl_ <1-x>和β-hfncl_ <1-x>，开发了一种新的电子掺杂方法，这些方法在很长一段时间内在空气中稳定。去解释的样品显示出与碱金属插入掺杂的电子相似的超导性。3。制备同位素取代的β-HF^<15> NCl，其超导体通过电子掺杂得出。4。 ^<15> N NMR研究表明，层结构的氮化层超导体是二维载体密度非常低的二维和弱语音增强的二维。新超导体的机制无法在常规BCS理论中解释5。超导差距通过分流方法成功测量。6。通过MBE方法在具有氮自由基的高真空室中通过MBE方法制备层结构化的SR_2N膜。