Lau Alexander, Koepernik Klaus, van den Brink Jeroen, Ortix Carmine
Institute for Theoretical Solid State Physics, IFW Dresden, 01171 Dresden, Germany.
Institute for Theoretical Physics, TU Dresden, 01069 Dresden, Germany.
Phys Rev Lett. 2017 Aug 18;119(7):076801. doi: 10.1103/PhysRevLett.119.076801.
The hallmark of Weyl semimetals is the existence of open constant-energy contours on their surface-the so-called Fermi arcs-connecting Weyl points. Here, we show that, for time-reversal symmetric realizations of Weyl semimetals, these Fermi arcs, in many cases, coexist with closed Fermi pockets originating from surface Dirac cones pinned to time-reversal invariant momenta. The existence of Fermi pockets is required for certain Fermi-arc connectivities due to additional restrictions imposed by the six Z_{2} topological invariants characterizing a generic time-reversal invariant Weyl semimetal. We show that a change of the Fermi-arc connectivity generally leads to a different topology of the surface Fermi surface and identify the half-Heusler compound LaPtBi under in-plane compressive strain as a material that realizes this surface Lifshitz transition. We also discuss universal features of this coexistence in quasiparticle interference spectra.
外尔半金属的标志是其表面存在开放的等能轮廓线——即所谓的连接外尔点的费米弧。在此，我们表明，对于时间反演对称的外尔半金属实现，在许多情况下，这些费米弧与源自钉扎在时间反演不变动量处的表面狄拉克锥的封闭费米口袋共存。由于表征一般时间反演不变外尔半金属的六个Z₂拓扑不变量施加的额外限制，某些费米弧连通性需要费米口袋的存在。我们表明，费米弧连通性的变化通常会导致表面费米面的不同拓扑结构，并确定面内压缩应变下的半赫斯勒化合物LaPtBi为实现这种表面里夫希茨转变的材料。我们还讨论了准粒子干涉谱中这种共存的普遍特征。
