New half-metallic materials with an alkaline earth element
New half-metallic materials with an alkaline earth element
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DOI：
10.1088/0953-8984/16/48/021
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发表时间：
2004-12
期刊：
影响因子：
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通讯作者：
K. Kusakabe;M. Geshi;Hidekazu Tsukamoto;N. Suzuki
中科院分区：
文献类型：
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作者：
K. Kusakabe;M. Geshi;Hidekazu Tsukamoto;N. Suzuki
Geshi等人最近从理论上设计了一种新的半金属材料候选物，即磷族钙化合物，即CaP、CaAs和CaSb。当假定为锌-砷结构时，这些化合物呈现半金属电子能带结构，其中发现了一个奇怪的平带，为了解释这种磁性，我们研究了CaAs的这个平带上的轨道特征。p态的作为与d态的钙的杂交被证明是必不可少的形成一个平面带的本地化轨道。在平带中完全自旋极化的出现表明平带机制与铁磁性有关。从第一性原理的结果与一个可解的Hubbard模型与一个平带的连接进行了讨论。
New candidates for half-metallic materials were theoretically designed recently by Geshi et al. The materials are calcium pnictides, i.e. CaP, CaAs and CaSb. When the zinc-blende structure was assumed, these compounds showed half-metallic electronic band-structure, in which a curious flat band was found. To explain this magnetism, we investigated characters of orbitals on this flat band of CaAs. The hybridization of p states of As with d states of Ca is shown to be essential for formation of a flat band made of localized orbitals. The appearance of complete spin polarization in the flat band suggests that the flat-band mechanism is relevant for the ferromagnetism. A connection from the first-principles result to a solvable Hubbard model with a flat band is discussed.