Three Quantum-Geometric Contributions to Cubic Orbital Magnetization

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1. Verfasser: Farajollahpour, T.
Format: Preprint
Veröffentlicht: 2026
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author Farajollahpour, T.
author_facet Farajollahpour, T.
contents In noncentrosymmetric metals such as $C_{3v}$ topological-insulator surfaces, moiré heterobilayers, and zincblende crystals, point-group symmetry can forbid the linear and quadratic electric-field-induced orbital magnetization, leaving the cubic response as the leading signal. Using a Ward-complete finite-momentum cubic Kubo kernel with an antisymmetric linear-in-$q$ projection, we show that the dc response separates into three quantum-geometric channels. These are a mixed electric-magnetic positional-shift quadrupole, a quantum-metric drift term, and an orbital-moment octupole. The three contributions share the same point-group symmetry but differ in their lifetime, frequency, and gate fingerprints. For a warped $C_{3v}$ surface the metric channel obeys the cutoff-independent law $\barχ_G \propto μ^{-2}$. We propose third-harmonic magneto-optical Kerr spectroscopy as an experimental route.
format Preprint
id arxiv_https___arxiv_org_abs_2605_27277
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Three Quantum-Geometric Contributions to Cubic Orbital Magnetization
Farajollahpour, T.
Mesoscale and Nanoscale Physics
In noncentrosymmetric metals such as $C_{3v}$ topological-insulator surfaces, moiré heterobilayers, and zincblende crystals, point-group symmetry can forbid the linear and quadratic electric-field-induced orbital magnetization, leaving the cubic response as the leading signal. Using a Ward-complete finite-momentum cubic Kubo kernel with an antisymmetric linear-in-$q$ projection, we show that the dc response separates into three quantum-geometric channels. These are a mixed electric-magnetic positional-shift quadrupole, a quantum-metric drift term, and an orbital-moment octupole. The three contributions share the same point-group symmetry but differ in their lifetime, frequency, and gate fingerprints. For a warped $C_{3v}$ surface the metric channel obeys the cutoff-independent law $\barχ_G \propto μ^{-2}$. We propose third-harmonic magneto-optical Kerr spectroscopy as an experimental route.
title Three Quantum-Geometric Contributions to Cubic Orbital Magnetization
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2605.27277