A blueprint for realizing the elusive gyrotropic magnetic effect with bicircular light
Science China PressPeer-Reviewed Publication
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, the research team theoretically propose a robust scheme to generate a significant GME in anisotropic nodal-line semimetals using Floquet engineering with bicircular light. They show that bicircular light 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, they 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. This 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.
- Journal
- Science Bulletin