Intrinsic negative magnetoresistance from the chiral anomaly of multifold fermions

Abstract

The chiral anomaly, a hallmark of chiral spin-1/2 Weyl fermions, is an imbalance between left- and right-moving particles that underpins both high and low energy phenomena, including particle decay and negative longitudinal magnetoresistance in Weyl semimetals. The discovery that chiral crystals can host higher-spin generalizations of Weyl quasiparticles without high-energy counterparts, known as multifold fermions, raises the fundamental question of whether the chiral anomaly is a more general phenomenon. Answering this question requires materials with chiral quasiparticles within a sizable energy window around the Fermi level, that are unaffected by trivial extrinsic effects such as current jetting. Here we report the chiral anomaly of multifold fermions in CoSi, which features multifold bands within about 0.85 eV around the Fermi level. By excluding current jetting through the squeezing test, we measure an intrinsic, longitudinal negative magnetoresistance. We develop the semiclassical theory of magnetotransport of multifold fermions that shows that the negative magnetoresistance originates in their chiral anomaly, despite a sizable and detrimental orbital magnetic moment contribution, previously unaccounted for. A concomitant nonlinear Hall effect supports the multifold-fermion origin of magnetotransport. Our work confirms the chiral anomaly of higher-spin generalizations of Weyl fermions, currently inaccessible outside the solid-state.

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Cited by in corpus (10)

• Linear response in planar Hall and thermal Hall setups for Rarita-Schwinger-Weyl semimetals
• Signatures of topology in generic transport measurements for Rarita-Schwinger-Weyl semimetals
• Reflections of topological properties in the planar-Hall response for semimetals carrying pseudospin-1 quantum numbers
• Chiral anomaly and internode scatterings in multifold semimetals
• Band Curvature Effects on Quantum Transport of Spin-1 Chiral Fermion Systems
• Winding Topology of Multifold Exceptional Points
• Disentangling contributions to longitudinal magnetoconductivity for Kramers-Weyl nodes
• Magnetoresistance in the Extreme Quantum Limit: Field-Induced Crossover to the Unitarity Limit
• Distinguishing features of longitudinal magnetoconductivity for a Rarita-Schwinger-Weyl node
• Symmetry-adapted models for multifold fermions with spin-orbit coupling