Crystal time-reversal symmetry breaking and spontaneous Hall effect in collinear antiferromagnets

By L. vSmejkal, R. González-Hernández, T. Jungwirth, J. Sinova. Science Advances, 2019

955 citations recorded by the source corpus.

Identification of a previously overlooked spontaneous Hall effect mechanism creates opportunities in low-dissipation spintronics. Electrons, commonly moving along the applied electric field, acquire in certain magnets a dissipationless transverse velocity. This spontaneous Hall effect, found more than a century ago, has been understood in terms of the time-reversal symmetry breaking by the internal spin structure of a ferromagnetic, noncolinear antiferromagnetic, or skyrmionic form. Here, we identify previously overlooked robust Hall effect mechanism arising from collinear antiferromagnetism combined with nonmagnetic atoms at noncentrosymmetric positions. We predict a large magnitude of this crystal Hall effect in a room temperature collinear antiferromagnet RuO2 and catalog, based on symmetry rules, extensive families of material candidates. We show that the crystal Hall effect is accompanied by the possibility to control its sign by the crystal chirality. We illustrate that accounting for the full magnetization density distribution instead of the simplified spin structure sheds new light on symmetry breaking phenomena in magnets and opens an alternative avenue toward low-dissipation nanoelectronics.

Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics

View Paper: https://www.semanticscholar.org/paper/0f1fb08d3e21763ab2807b6a74224faa999f9d6f

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In Atomic and Molecular Physics, and Optics

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Citations in the corpus

Crystal-symmetry-paired spin–valley locking in a layered room-temperature metallic altermagnet candidate (2024, neutral): “As for RuO 2 , it remains controversial whether its ground state is antiferromagnetic 33,34 or non-magnetic 32 , despite evidence of an anomalous Hall effect 16,30 and spin splitting 31,38 .”
Topological superconductivity in two-dimensional altermagnetic metals (2023, background): “Recently, it has been observed in a series of materials with compensated magnetization that a third basic collinear magnetic order 16–29 , referred to as altermagnetism (AM) 30–32 , exists beyond the conventional dichotomy between ferromag-netism and antiferromagnetism.”
Absence of magnetic order in RuO2: insights from μSR spectroscopy and neutron diffraction (2024, methodology): “…better interpret the results of the µ SR measurements, we performed first-principles calculations based on spin-polarized density functional theory (DFT), and enforcing a magnetic moment on the Ru atoms by adding a large effective Hubbard U [22], as also done in other computational studies [4, 23].”
Altermagnetism with non-collinear spins (2024, background): “However, through symmetry considerations, we have demonstrated that rather than a fresh class, altermagnetism is a practically useful concept to introduce PT proposed for collinear spins are inside of dashed circle 18 , and all type-I altermagnets belong to the ferromagnetic point group.”
A metallic room-temperature d-wave altermagnet (2024, positive): “Recent theoretical studies have pointed out that non-relativistic spin splitting can exist in certain magnets with zero net magnetization, even without spin-orbit coupling, leading to the concept of altermagnetism [1-14].”
Beyond skyrmions: Review and perspectives of alternative magnetic quasiparticles (2020, background): “Also the anomalous Hall effect in several coplanar Kagome magnets without net magnetization [91, 92, 93, 94, 95] and the crystal Hall effect for which a set of time reversal and spatial symmetries is broken by the arrangement of non-magnetic atoms in the crystal [96, 97] have been predicted and meas”