通过金属化σ电子寻找高温超导体  

Finding high-temperature superconductors by metallizing the σ-bonding electrons

作　　者：高淼[1] 卢仲毅[2] 向涛[1,3] 

机构地区：[1]中国科学院物理研究所,北京100190 [2]中国人民大学物理系,北京100872 [3]量子物质科学协同创新中心,北京100190

出　　处：《物理》2015年第7期421-426,共6页Physics

基　　金：国家重点基础研究发展计划(批准号:2011CBA00112);国家自然科学基金(批准号:11190024;11404383);中国博士后科学基金(批准号:2014M561084)资助项目

摘　　要：提高超导相变温度是超导基础研究的一个重要目标,也是超导广泛应用的一个前提。在高温超导微观机理尚不清楚的情况下,寻找高温超导体一般是通过对材料施加高压或通过掺杂使材料尽可能地接近反铁磁或其他量子不稳定点来实现。这篇文章介绍的是一种通过金属化σ电子能带来提高超导相变温度的方法。这种方法之所以有效,能够提高发现新的高温超导体的概率,是因为σ电子与声子之间通常存在很强的相互作用,可以显著增强电子的超导配对能,从而提升超导相变温度。作者以具体材料为例介绍了金属化σ能带的几种可行途径,并介绍了他们最近预言的两个相变温度可能超过50 K的超导体Li3B4C2与Li2B3C的晶体及电子结构。Raising superconducting transition temperature（Tc） is an important task of fundamental research on superconductivity. It is also a prerequisite for the large scale application of superconductors. Since the microscopic mechanism of high-Tcsuperconductivity is unknown, the conventional approach for increasing Tcis either to apply high pressure to a material which has the potential to become superconducting, or to push it close to an antiferromagnetic or some other quantum instability point by chemical doping. In this article, the authors point out that another general approach for raising Tcis to lift the σ-bonding bands to the Fermi level, or to metalize theσ-bonding elections. This approach can increase the probability of finding a novel high-Tcsuperconductor because the coupling of σ- bonding electrons with phonons is generally strong and the superconducting transition induced by this interaction can occur at relatively high temperatures.After elucidating the underlying mechanism, the authors discuss a number of schemes to metalizeσ-bonding electrons, and present their recent prediction for the crystalline and electronic structures of two potential high-Tcsuperconductors, Li2B3 C and Li3B4C2, with Tchigher than 50 K.

关 键 词：超导电性 电声耦合 第一性原理计算 

分 类 号：O511.3[一般工业技术—材料科学与工程]