Emptying Dirac valleys in bismuth using high magnetic fields

Abstract

The Fermi surface of elemental bismuth consists of three small rotationally equivalent electron pockets, offering a valley degree of freedom to charge carriers. A relatively small magnetic field can confine electrons to their lowest Landau level. This is the quantum limit attained in other dilute metals upon application of sufficiently strong magnetic field. Here, we report on the observation of another threshold magnetic field never encountered before in any other solid. Above this field, $B_{\mathrm{empty}}$, one or two valleys become totally empty. Drying up a Fermi sea by magnetic field in the Brillouin zone leads to a manyfold enhancement in electric conductance. We trace the origin of the large drop in magnetoresistance across $B_{\mathrm{empty}}$ to transfer of carriers between valleys with highly anisotropic mobilities. The non-interacting picture of electrons with field-dependent mobility explains most results. Coulomb interaction may play a role in shaping the fine details.

19 pages, 5 figures, Supplemental Material available upon request

References in corpus (10)

• Valley filter and valley valve in graphene
• Titanic Magnetoresistance in WTe2
• Extremely large magnetoresistance and ultrahigh mobility in the topological Weyl semimetal NbP
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• Linear magnetoresistance in metals: guiding center diffusion in a smooth random potential
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• Origin of the large anisotropic g-factor of holes in bismuth
• Valley polarization assisted spin polarization in two dimensions
• Landau spectrum and twin boundaries of bismuth in the extreme quantum limit
• Parallel Magnetic Field Tuning of Valley Splitting in AlAs Two-Dimensional Electrons

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• The magnetoelectric coupling in Electrodynamics
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• Metamagnetic multiband Hall effect in Ising antiferromagnet ErGa${}_2$
• Critical point for Bose-Einstein condensation of excitons in graphite
• Realization of a Valley Superlattice
• Metallic state in a strongly interacting spinless two-valley electron system in two dimensions
• Angular dependence of magnetoresistance and planar Hall effect in semimetals in strong magnetic fields
• Boundary conductance in macroscopic bismuth crystals
• Ground-state atlas of a three-dimensional semimetal in the quantum limit
• Wide critical fluctuations of the field-induced phase transition in graphite
• Sizable spin-transfer torque in Bi/Ni80Fe20 bilayer film
• A field-induced reentrant insulator state of a gap-closed topological insulator (Bi_{1-x}Sb_x) in quantum-limit states
• Effects of strain-tunable valleys on charge transport in bismuth
• Quantum--classical correspondence and dissipative to dissipationless crossover in magnetotransport phenomena
• Anomalous Hall Effect in Thin Bismuth
• High-field immiscibility of electrons belonging to adjacent twinned bismuth crystals
• Magnetoresistance in the Extreme Quantum Limit: Field-Induced Crossover to the Unitarity Limit
• Impact of spin--orbit coupling on orbital diamagnetism in a narrow-gap semiconductor ${\mathrm{Pb}}_{1-x}{\mathrm{Sn}}_x\mathrm{Te}$
• Spin and valley effects on the quantum phase transition in two dimensions