Spin and Charge Photocurrents from Electric-Magnetic Dipole Interference in Centrosymmetric Crystals
Abstract
A common view regarding even-order nonlinear optical (NLO) effects, such as second-harmonic generation and the bulk photovoltaic effect, is that the breaking of inversion symmetry is necessary. However, this view relies on the assumption that light interacts with materials solely through its electric field. Here, we demonstrate that interference between the electric and magnetic components of the same light field can induce even-order NLO effects even in centrosymmetric materials. Using charge and spin photocurrents as prototypical examples, we present a unified microscopic theory showing how such electric-magnetic dipole interference (EMDI) drives NLO responses in inversion-symmetric crystals. Bilinear in both electric and magnetic fields, these responses scale linearly with light intensity. Combining symmetry analysis with first-principles calculations, we decompose the EMDI-induced photocurrents into shift-like and injection-like contributions and classify their dependence on crystal symmetry, time-reversal symmetry, and light polarization. Notably, we reveal that these EMDI-induced responses in centrosymmetric materials are weaker than conventional responses in non-centrosymmetric materials roughly by a factor of fine structure constant $α\approx [10^{-3}\text{--}10^{-2}] $. Nevertheless, they remain well within experimental reach. Our work thus unlocks NLO functionalities in centrosymmetric materials for e.g., materials characterization, photonics and optoelectronics. This is vital given that many functionally importantly materials, such as cubic Si and cubic SrTiO3, possess inversion symmetry.
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BibTeX
@misc{zhao2026spin,
title = {{Spin and Charge Photocurrents from Electric-Magnetic Dipole Interference in Centrosymmetric Crystals}},
author = {Yiwei Zhao and Jian Zhou and Haowei Xu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.34222},
eprint = {2610.34222},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.34222},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Spin and Charge Photocurrents from Electric-Magnetic Dipole Interference in Centrosymmetric Crystals
AU - Yiwei Zhao
AU - Jian Zhou
AU - Haowei Xu
PY - 2026
DA - 2026/10/25
PB - arXiv
DO - 10.48550/arxiv.2610.34222
UR - https://arxiv.org/abs/2610.34222
AB - A common view regarding even-order nonlinear optical (NLO) effects, such as second-harmonic generation and the bulk photovoltaic effect, is that the breaking of inversion symmetry is necessary. However, this view relies on the assumption that light interacts with materials solely through its electric field. Here, we demonstrate that interference between the electric and magnetic components of the same light field can induce even-order NLO effects even in centrosymmetric materials. Using charge and spin photocurrents as prototypical examples, we present a unified microscopic theory showing how such electric-magnetic dipole interference (EMDI) drives NLO responses in inversion-symmetric crystals. Bilinear in both electric and magnetic fields, these responses scale linearly with light intensity. Combining symmetry analysis with first-principles calculations, we decompose the EMDI-induced photocurrents into shift-like and injection-like contributions and classify their dependence on crystal symmetry, time-reversal symmetry, and light polarization. Notably, we reveal that these EMDI-induced responses in centrosymmetric materials are weaker than conventional responses in non-centrosymmetric materials roughly by a factor of fine structure constant $α\approx [10^{-3}\text{--}10^{-2}] $. Nevertheless, they remain well within experimental reach. Our work thus unlocks NLO functionalities in centrosymmetric materials for e.g., materials characterization, photonics and optoelectronics. This is vital given that many functionally importantly materials, such as cubic Si and cubic SrTiO_3, possess inversion symmetry.
ER -