Yb硫族化合物YbO和YbS中压力驱动的拓扑相变
Pressure-Driven Topological Phase Transition in the Yb Chalcogenides YbO and YbS
摘要：
采用基于密度泛函理论的第一性原理计算，采用修正的Becke-Johnson局域密度近似加Hubbard U（MBJLDA+U），研究了Yb硫属化合物YbO和YbS在常压和高压下的能带结构.结果表明，在常压下，YbO和YbS都具有平凡的能带拓扑结构，而在高压下则具有非平凡的能带拓扑结构。拓扑相变是由压力驱动的5d-和4f -轨道之间的时间反演不变动量（TRIM）点X的单带反转减少。在[001]表面上通过紧束缚模型计算确定的一对金属表面态共存的体狄拉克锥也证明了高压下YbO和YbS的非平凡能带拓扑。
英文摘要：
By first-principles calculation based on the density functional theory (DFT) with the modified Becke-Johnson local density approximation plus Hubbard U (MBJLDA+U), we studied the band structures of the Yb chalcogenides YbO and YbS under ambient and high pressures. It was revealed that both YbO and YbS have a trivial band topology under ambient pressure, and a nontrivial band topology under high pressure. The topological phase transition is reduced by the pressure-driven single-band inversion between 5d- and 4f -orbitals at the time-reversal invariant momentum (TRIM) point X. A bulk Dirac cone coexisting with a pair of metallic surface states on the [001] surface determined by tight binding model calculation with a slab geometry also demonstrates the nontrivial band topology of YbO and YbS under high pressure.
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