Experimental evidence for Berry curvature multipoles in antiferromagnets

Abstract

Berry curvature multipoles appearing in topological quantum materials have recently attracted much attention. Their presence can manifest in novel phenomena, such as nonlinear anomalous Hall effects (NLAHE). The notion of Berry curvature multipoles extends our understanding of Berry curvature effects on the material properties. Hence, research on this subject is of fundamental importance and may also enable future applications in energy harvesting and high-frequency technology. It was shown that a Berry curvature dipole can give rise to a 2nd order NLAHE in materials of low crystalline symmetry. Here, we demonstrate a fundamentally new mechanism for Berry curvature multipoles in antiferromagnets that are supported by the underlying magnetic symmetries. Carrying out electric transport measurements on the kagome antiferromagnet FeSn, we observe a 3rd order NLAHE, which appears as a transverse voltage response at the 3rd harmonic frequency when a longitudinal a.c. current drive is applied. Interestingly, this NLAHE is strongest at and above room temperature. We combine these measurements with a scaling law analysis, a symmetry analysis, model calculations, first-principle calculations, and magnetic Monte-Carlo simulations to show that the observed NLAHE is induced by a Berry curvature quadrupole appearing in the spin-canted state of FeSn. At a practical level, our study establishes NLAHE as a sensitive probe of antiferromagnetic phase transitions in other materials, such as moiré superlattices, two-dimensional van der Waal magnets, and quantum spin liquid candidates, that remain poorly understood to date. More broadly, Berry curvature multipole effects are predicted to exist for 90 magnetic point groups. Hence, our work opens a new research area to study a variety of topological magnetic materials through nonlinear measurement protocols.

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• Quantum geometry encoded to pair potentials
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• Light-induced charge and spin Hall currents in materials with $C_{4}K$ symmetry
• Giant Third-Order Nonlinearity Induced by the Quantum Metric Quadrupole in Few-Layer WTe2
• Intrinsic gyrotropic magnetic current from Zeeman quantum geometry
• Second harmonic generation induced by gate voltage oscillation in few layer MnBi2Te4
• Nonlinear anomalous transverse responses induced by Berry curvature quadrupole in systems with broken time-reversal symmetry
• The "Sign problem" of the 3rd order anomalous Hall effect in topological magnetic materials
• Role of Disorder in Third-order Anomalous Hall Effect in Time-reversal Symmetric Systems
• Band Geometry Induced Third-Harmonic Generation
• Orbital magnetization as the origin of the nonlinear Hall effect
• Identifying geometric third-order nonlinear transport in disordered materials
• Electric field controlled second-order anomalous Hall effect in altermagnets
• Ferroelectric-tunable quantum nonlinearity of chiral Bloch electrons in a moiré system
• Third-order nonlinear transport in a percolative two-dimensional superconductor
• High-pressure modulation of breathing kagome lattice: Cascade of Lifshitz transitions and evolution of the electronic structure
• Quantum geometric map of magnetotransport