Antisymmetric linear magnetoresistance and the planar Hall effect

Abstract

The phenomena of antisymmetric magnetoresistance and the planar Hall effect are deeply entwined with ferromagnetism. The intrinsic magnetization of the ordered state permits these unusual and rarely observed manifestations of Onsager's theorem when time reversal symmetry is broken at zero applied field. Here we study two classes of ferromagnetic materials, rare-earth magnets with high intrinsic coercivity and antiferromagnetic pyrochlores with strongly-pinned ferromagnetic domain walls, which both exhibit antisymmetric magnetoresistive behavior. By mapping out the peculiar angular variation of the antisymmetric galvanomagnetic response with respect to the relative alignments of the magnetization, magnetic field, and electrical current, we experimentally distinguish two distinct underlying microscopic mechanisms: namely, spin-dependent scattering of a Zeeman-shifted Fermi surface and anomalous electron velocities. Our work demonstrates that the anomalous electron velocity physics typically associated with the anomalous Hall effect is prevalent beyond the ρ xy (H z) channel, and should be understood as a part of the general galvanomagnetic behavior.

A continuous metal-insulator transition driven by spin correlations

“…Extracting the bulk Hall coefficient. The highly coercive, fieldindependent magnetization M of the conductive ferromagnetic domain walls necessarily introduces antisymmetric linear MR 21 that makes the Hall resistances of the two reciprocal channels, R 12,34 (H, M) and R 43,12 (H, M), have different linear slopes with H (Fig. 2c).…”

“…2a, b, Methods, and ref. 21 ). Here we first examine the ϕ-dependences of the Hall resistivity slopes from two reciprocal channels R Hall1…”

“…Ferromagnetic domain walls introduce a Zeeman shift in the metallic paramagnetic band structure, but they are not expected to gap the Fermi surface like the antiferromagnetic bulk, and they are expected to remain metallic down to T = 0. As was pointed out recently 21 , the highly coercive metallic ferromagnetic domain walls generate antisymmetric linear magnetoresistance (MR) of the same functional form as the Hall resistance. Moreover, the antisymmetric linear MR is detectable in Hall channels due to the distorted current paths through the domain walls 21 .…”

“…As was pointed out recently 21 , the highly coercive metallic ferromagnetic domain walls generate antisymmetric linear magnetoresistance (MR) of the same functional form as the Hall resistance. Moreover, the antisymmetric linear MR is detectable in Hall channels due to the distorted current paths through the domain walls 21 . This effect is likely the root cause of the widely varying Hall coefficient reported in the literature for Cd 2 Os 2 O 7 9,16 , as the standard procedure for extracting Hall resistance through antisymmetrization with respect to magnetic field direction leads to erroneous results.…”

“…There exists an additional challenge arising from complications in modeling and understanding the transport data in many 5d AIAO antiferromagnets due to the intrinsically conductive and highly coercive ferromagnetic domain walls 9,[19][20][21] . Ferromagnetic domain walls introduce a Zeeman shift in the metallic paramagnetic band structure, but they are not expected to gap the Fermi surface like the antiferromagnetic bulk, and they are expected to remain metallic down to T = 0.…”