Tunable spin-valley coupling in layered polar Dirac metals

Abstract

In non-centrosymmetric metals, spin-orbit coupling (SOC) induces momentum-dependent spin polarization at the Fermi surfaces. This is exemplified by the valley-contrasting spin polarization in monolayer transition metal dichalcogenides (TMDCs) with in-plane inversion asymmetry. However, the valley configuration of massive Dirac fermions in TMDCs is fixed by the graphene-like structure, which limits the variety of spin-valley coupling. Here, we show that the layered polar metal BaMn$X_2$ ($X=$Bi, Sb) hosts tunable spin-valley-coupled Dirac fermions, which originate from the distorted $X$ square net with in-plane lattice polarization. We found that in spite of the larger SOC, BaMnBi${}_2$ has approximately one-tenth the lattice distortion of BaMnSb${}_2$, from which a different configuration of spin-polarized Dirac valleys is theoretically predicted. This was experimentally observed as a clear difference in the Shubnikov-de Haas oscillation at high fields between the two materials. The chemically tunable spin-valley coupling in BaMn$X_2$ makes it a promising material for various spin-valleytronic devices.

arXiv comment25 pages, 4 figures. Published in Communications Materials

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Cited by in corpus (5)

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• High-field Studies on Layered Magnetic and Polar Dirac Metals
• Nonreciprocal charge transport in polar Dirac metals with tunable spin-valley coupling
• C-type antiferromagnetic structure of topological semimetal CaMnSb${}_2$
• Evidence of Spin-Valley Coupling in Dirac Material BaMnBi2 Probed by Quantum Hall Effect and Nonlinear Hall Effect