La-Substituted CaFeAsH Superconductor with Tc=47K
La-Substituted CaFeAsH Superconductor with Tc=47K
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DOI：
10.7566/jpsj.83.033705
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发表时间：
2014-03-01
影响因子：
1.7
通讯作者：
Hosono, Hideo
中科院分区：
文献类型：
--
作者：
Muraba, Yoshinori;Matsuishi, Satoru;Hosono, Hideo
在1173 K和2.5GPa的高压下，通过固相反应合成了La取代的CaFeAsH，即（Ca 1-xLax）FeAsH。La取代抑制了四方晶系到正交晶系结构转变所对应的rho-T反常，在电子掺杂量N-e > 0.05时观察到超导电性。当N-e = 0.18时，达到47.4K的最大起始T-c，这与通过Co取代到Fe位而将电子直接掺杂到FeAs层所实现的23 K相比是显著增加的。该Tc值与间接电子掺杂LnFeAsO（Ln = La）中As-Fe-As键角与Tc之间的唯象关系符合得很好。这些结果表明，电子是通过异价离子对CaH层的替代（Ca ~（2+）-> La ~（3+）+ e（-））以间接方式掺杂的。
La-substituted CaFeAsH, (Ca1-xLax)FeAsH, were synthesized by the solid state reaction at 1173K under high pressure of 2.5 GPa. The rho-T anomaly corresponding to tetragonal to orthorhombic structural transition was suppressed by La-substitution and then the superconductivity was observed at an electron doping content of N-e > 0.05. The maximum onset T-c of 47.4K was reached for N-e = 0.18, which is significant increase compared to 23K achieved by direct electron doping to the FeAs-layer via Co-substitution to the Fe-site. This value of T-c value fits well to the phenomenological relation between T-c and the bond angle of As-Fe-As in indirectly electron doped LnFeAsO (Ln = Lanthanide). These results indicate that the electron was doped via the indirect mode through the aliovalent ion substitution to CaH-layer (Ca2+ -> La3+ + e(-)).