*

The study of Quantum Hall effect (QHE) in two-dimensional (2D) systems such as 2D electron gas and graphene has led to important breakthroughs in the development of many new concepts in modern physics. Although the QHE is not generally expected for bulk materials due to the band dispersion along the magnetic field direction, bulk QHE has been observed in a few materials such as Cd₃As₂ (1), ZrTe₅ (2) and EuMnBi₂ (3). In this talk, we report a unique bulk half-integer QHE observed in a layered Dirac semimetal BaMnSb₂. In the extreme quantum limit, its quantum Hall state is accompanied by two-dimensional chiral metal at the surface, which represents a novel quantum liquid, never observed in any other bulk single crystal materials [4]. This finding establishes a promising experimental platform which not only provides access to 3D interacting topological states, but also offers opportunities to investigate the novel physics of 2D chiral metal.
References:
1. C. Zhang et al., Nature. 565, 331 (2019).
2. F. Tang et al., Nature. 569, 537 (2019).
3. H. Masuda et al., Science Advances. 2, e1501117 (2016).
4. J.Y. Liu et al., arXiv:1907.06318