Gyrotropic Magnetic Effect in Black Phosphorus Irradiated with Bicircular Light

TL;DR

This paper proposes a method to induce and enhance the gyrotropic magnetic effect in black phosphorus using bicircular light, enabling experimental observation and control of topological electronic properties in anisotropic semimetals.

Contribution

It introduces a Floquet engineering scheme with bicircular light to generate a significant GME in black phosphorus, a novel approach for manipulating topological phases.

Findings

Bicircular light induces a topological phase transition in black phosphorus.

The GME in black phosphorus is amplified by its intrinsic anisotropy.

The proposed method predicts a measurable gyrotropic current orders of magnitude larger than previous systems.

Abstract

The gyrotropic magnetic effect (GME), which emerges as the low-frequency limit of natural gyrotopy, is a fundamental property of Bloch electrons on the Fermi surface in materials lacking inversion symmetry. While Weyl semimetals were among the first systems predicted to host the GME, this effect has not yet been experimentally observed in these materials. Here, we theoretically propose a robust scheme to generate a significant GME in anisotropic nodal-line semimetals using Floquet engineering with bicircular light (BCL). We show that BCL irradiation can selectively break spatial and time-reversal symmetries, inducing a topological phase transition from a nodal-line semimetal to a Weyl semimetal with a minimal number of Weyl nodes. Crucially, the Weyl nodes with opposite chirality are separated in energy, a key requirement for a non-zero GME. Using first-principles calculations combined with Floquet theory, we identify compressed black phosphorus as an ideal material platform. The intrinsic anisotropy of black phosphorus amplifies the GME, resulting in a measurable gyrotropic current that is several orders of magnitude larger than that in previously proposed systems. Our work not only provides a concrete path toward the experimental realization of GME but also opens new avenues for exploring the interplay of light, symmetry, and topology in quantum materials.