Formation Mechanism of Hybridization Gap in Kondo Insulators based on a Realistic Band Model and Application to YbB12
Formation Mechanism of Hybridization Gap in Kondo Insulators based on a Realistic Band Model and Application to YbB12
复制标题
基于现实能带模型的近藤绝缘子杂化间隙形成机制及其在YbB12中的应用
DOI：
10.1143/jpsj.72.1131
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发表时间：
2003
影响因子：
1.7
通讯作者：
H. Harima
中科院分区：
文献类型：
--
作者：
T. Saso;H. Harima
对近藤绝缘体材料YbB 12进行了新的LDA+U能带计算，得到了约为0.001赖德的能隙.在此基础上，建立了一个简单的紧束缚模型，该模型考虑了Yb原子上的5d e和4f Γ 8轨道以及它们之间的最近邻σ键，与差距附近的LDA+U计算结果符合得很好.态密度也被计算和形状被发现是非常不对称的差距。利用导带和f态的轨道简并，首次在实际情况下阐明了差距的形成机制。该模型可以成为纳入强相关效应以及理解YbB 12的所有热、热电、输运和磁性质的有用起点。
A new LDA+U band calculation is performed on the Kondo insulator material YbB 12 and an energy gap of about 0.001 Ryd is obtained. Based on this, a simple tight-binding model with 5d e and 4f Γ 8 orbitals on Yb atoms and the nearest neighbor σ-bonds between them is constructed with a good agreement to the above the LDA+U calculation near the gap. The density of states is also calculated and the shape is found to be very asymmetric with respect to the gap. A formation mechanism of the gap is clarified for the first time in a realistic situation with the orbital degeneracies in both conduction bands and the f states. This model can be a useful starting point for incorporating the strong correlation effect, and for understanding all the thermal, thermoelectric, transport and magnetic properties of YbB 12 .