Chern Semimetal and the Quantized Anomalous Hall Effect in HgCr 2 Se 4

作者：Gang Xu, Hongming Weng, Zhijun Wang, Xi Dai, Zhong Fang · 发表于：Physical Review Letters · 年份：2011 · DOI：10.1103/physrevlett.107.186806 · 被引用次数：1503 · 研究领域：Topological Materials and Phenomena、Advanced Condensed Matter Physics、Graphene research and applications

In 3D momentum space, a topological phase boundary separating the Chern insulating layers from normal insulating layers may exist, where the gap must be closed, resulting in a "Chern semimetal" state with topologically unavoidable band crossings at the Fermi level. This state is a condensed-matter realization of Weyl fermions in (3+1)D, and should exhibit remarkable features, such as magnetic monopoles and Fermi arcs. Here we predict, based on first principles calculations, that such a novel quantum state can be realized in a known ferromagnetic compound HgCr2Se4, with a single pair of Weyl fermions separated in momentum space. The quantum Hall effect without an external magnetic field can be achieved in its quantum-well structure.