Bulk quantum Hall effect of spin-valley-coupled Dirac fermions in a polar antiferromagnet BaMnSb${}_2$

Abstract

Unconventional features of relativistic Dirac/Weyl quasi-particles in topological materials are most evidently manifested in the 2D quantum Hall effect (QHE), whose variety is further enriched by their spin and/or valley polarization. Although its extension to three dimensions has been long-sought and inspired theoretical proposals, material candidates have been lacking. Here we have discovered valley-contrasting spin-polarized Dirac fermions in a multilayer form in bulk antiferromagnet BaMnSb${}_2$, where the out-of-plane Zeeman-type spin splitting is induced by the in-plane inversion symmetry breaking and spin-orbit coupling (SOC) in the distorted Sb square net. Furthermore, we have observed well-defined quantized Hall plateaus together with vanishing interlayer conductivity at low temperatures as a hallmark of the half-integer QHE in a bulk form. The Hall conductance of each layer is found to be nearly quantized to $2(N+1/2)e^2/h$ with $N$ being the Landau index, which is consistent with two spin-polarized Dirac valleys protected by the strong spin-valley coupling.

14 pages, 4 figures. Accepted in Phys. Rev. B (Rapid Communication)

References in corpus (10)

• Unconventional Integer Quantum Hall effect in graphene
• A precise method for visualizing dispersive features in image plots
• Quantum Hall effect in a bulk antiferromagnet EuMnBi${}_2$ with magnetically confined two-dimensional Dirac fermions
• Quantum Hall Effect on Top and Bottom Surface States of Topological Insulator (Bi1-xSbx)2Te3 Films
• Unconventional Quantum Hall Effect and Tunable Spin Hall Effect in MoS2 Trilayers
• Effect of Eu magnetism on the electronic properties of the candidate Dirac material EuMnBi2
• Dirac and Normal Fermions in Graphite and Graphene: Implications to the Quantum Hall Effect
• Nontrivial Berry phase in magnetic BaMnSb2 semimetal
• Functionalized Bismuth Films: Giant Gap Quantum Spin Hall and Valley-Polarized Quantum Anomalous Hall States
• Observation of two-dimensional Fermi surface and Dirac dispersion in YbMnSb${}_2$

Cited by in corpus (14)

• Strong Room-Temperature Bulk Nonlinear Hall Effect in a Spin-Valley Locked Dirac Material
• Magnetic tuning of band topology evidenced by exotic quantum oscillations in the Dirac semimetal EuMnSb${}_2$
• Quantum-Hall physics and three dimensions
• Magnetotransport studies of the Sb square-net compound LaAgSb${}_2$ under high pressure and rotating magnetic fields
• High-field Studies on Layered Magnetic and Polar Dirac Metals
• Polarization Jumps across Topological Phase Transitions in Two-dimensional Systems
• Unusual Electronic Structure of Dirac Material BaMnSb${}_2$ Revealed by Angle-Resolved Photoemission Spectroscopy
• Nonreciprocal charge transport in polar Dirac metals with tunable spin-valley coupling
• Observation of quantum oscillations, linear magnetoresistance, and crystalline electric field effect in quasi-two-dimensional PrAgBi${}_2$
• Molecular beam deposition of a new layered pnictide with distorted Sb square nets
• Importance of the semimetallic state for the quantum Hall effect in HfTe${}_5$
• Inherited Berry curvature of phonons in Dirac materials with time-reversal symmetry
• Evidence of Spin-Valley Coupling in Dirac Material BaMnBi2 Probed by Quantum Hall Effect and Nonlinear Hall Effect
• Field-induced metal-to-insulator transition and colossal anisotropic magnetoresistance in a nearly Dirac material EuMnSb${}_2$