Spin-valley locking, bulk quantum Hall effect and chiral surface state in a noncentrosymmetric Dirac semimetal BaMnSb${}_2$

Abstract

Spin-valley locking in the band structure of monolayers of MoS${}_2$ and other group-VI dichalcogenides has attracted enormous interest, since it offers potential for valleytronic and optoelectronic applications. Such an exotic electronic state has sparsely been seen in bulk materials. Here, we report spin-valley locking in a bulk Dirac semimetal BaMnSb${}_2$. We find valley and spin are inherently coupled for both valence and conduction bands in this material. This is revealed by comprehensive studies using first principle calculations, tight-binding and effective model analyses, angle-resolved photoemission spectroscopy and quantum transport measurements. Moreover, this material also exhibits a stacked quantum Hall effect. The spin-valley degeneracy extracted from the plateau height of quantized Hall resistivity is close to 2. This result, together with the observed Landau level spin splitting, further confirms the spin-valley locking picture. In the extreme quantum limit, we have also observed a two-dimensional chiral metal at the side surface, which represents a novel topological quantum liquid. These findings establish BaMnSb${}_2$ as a rare platform for exploring coupled spin and valley physics in bulk single crystals and accessing 3D interacting topological states.

Updated acknowledgement

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• Strong Room-Temperature Bulk Nonlinear Hall Effect in a Spin-Valley Locked Dirac Material
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• Euler Obstructed Cooper Pairing: Nodal Superconductivity and Hinge Majorana Zero Modes
• Magnetic tuning of band topology evidenced by exotic quantum oscillations in the Dirac semimetal EuMnSb${}_2$
• Twisted nodal wires and three-dimensional quantum spin Hall effect in distorted square-net compounds
• Electronic Structure Examination on the Topological Properties of CaMnSb${}_2$ by Angle-Resolved Photoemission Spectroscopy
• Quantum-Hall physics and three dimensions
• Detection of phonon helicity in nonchiral crystals with Raman scattering
• Robustness of spin-polarized edge states in a two-dimensional topological semimetal without inversion symmetry
• 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
• Nonreciprocal charge transport in polar Dirac metals with tunable spin-valley coupling
• Stretching bonds in Density Functional Theory without artificial symmetry breaking
• Chalcogen Doping Effect on the Insulator-to-Metal Transition in GdPS
• Evidence of Spin-Valley Coupling in Dirac Material BaMnBi2 Probed by Quantum Hall Effect and Nonlinear Hall Effect
• Inherited Berry curvature of phonons in Dirac materials with time-reversal symmetry