掺氟对Y-Ba-Cu-O高温超导体电子结构的影响

INFLUENCES OF FLUORINE DOPING TO THE ELECTRONIC STRUCTURE OF THE Y-Ba-Cu-O SUPERCONDUCTORS

采用Recursion方法计算了不同掺氟量和不同替代位置下Y-Ba-Cu-O的电子结构,从掺氟Y-Ba-Cu-O各晶位的态密度(DOS),可进一步得到Fermi能EF、Fermi能级处的态密度N(EF)以及各晶位原子价等重要数据.各模型的计算结果表明,掺入氟后引起CuO2平面上Cu的原子价升高和O的价位变得更负,使Cu位空穴数目增加和O位空穴数目减少,且以后者的变化为主.掺氟改变了Y-Ba-Cu-O中CuO2平面上载流子的浓度,影响了电荷从CuO2平面向CuO链的转移,增加了Fermi面电子浓度,这可能是对高温氧化物超导电性产生影响的原因.

The electronic structures of fluorine-doped Y-Ba-Cu-O superconductors are calculated with Recursion method. The electronic density of states (DOS), Fermi energy (E-F), atomic valences of different elements are obtained. The results show that the valences of Cu atom increase and those of O atom decrease, which means that the amount of hole carrier of Cu increases and that of O decreases. Fluorine-doping changes hole carrier concentration in the CuO2 plane, and thus improves the superconducting properties of Y-Ba-Cu-O.