Magnetic bulk photovoltaic effect as a probe of magnetic structures of $EuSn_2As_2$

TL;DR

This study explores how the bulk photovoltaic effect in EuSn2As2 varies with different magnetic structures, proposing it as a tool to probe magnetic order through symmetry analysis and first-principles calculations.

Contribution

It demonstrates that BPVE responses depend on magnetic configurations in EuSn2As2, enabling magnetic structure identification via optical measurements.

Findings

AFM EuSn2As2 breaks inversion symmetry and exhibits second-order optical responses.

BPVE responses vary with magnetic moment orientation and phase symmetry.

Circularly polarized light can distinguish different magnetic structures.

Abstract

The bulk photovoltaic effect (BPVE) is a second-order optical process in noncentrosymmetric materials that converts the light into DC currents. BPVE is classified into shift current and injection current according to the generation mechanisms, whose dependence on the polarization of light is sensitive to the spatial and time-reversal symmetry of materials. In this work, we present a comprehensive study on the BPVE response of $EuSn_2As_2$ with different magnetic structures through symmetry analysis and first-principles calculation. We demonstrate that the interlayer antiferromagnetic (AFM) $EuSn_2As_2$ of even-layer breaks the inversion symmetry and has the second-order optical responses. Moreover, the bilayer AFM $EuSn_2As_2$ not only displays distinct BPVE responses when magnetic moments align in different directions, but also shows symmetry-related responses in two phases which have mutually perpendicular in-plane magnetic moments. Due to the dependence of BPVE responses on the polarization of light and magnetic symmetry, these magnetic structures can be distinguished by the circular polarized light with well-designed experiments. Our work demonstrates the feasibility of the BPVE response as a tool to probe the magnetic structure.