Chiral Phononics: How to Control Electronic Phases with Phonon Angular Momentum
Chiral phonons conventionally describe circularly polarized lattice vibrations that carry angular momentum. In dielectric materials, the circular motions of the ions create a macroscopic magnetic field when driven with an ultrashort laser pulse, which has previously been shown to reach the order of millitesla. Here, we predict that this magnetic field can effectively reach up to the tesla scale, when enhanced by orbit-lattice coupling [1,2]. Our predictions have been experimentally confirmed in a recent study [3]. We demonstrate theoretically that these giant phono-magnetic fields can be utilized to generate nonequilibrium spin configurations in antiferromagnets, leading to a light-induced weak ferromagnetic state [4]. Finally, whereas the above phenomena are based on circularly polarized chiral phonons, we further demonstrate that the crystal structure can be transiently made chiral with linearly polarized phonons that are quasistatically displaced by nonlinear phonon coupling [5]. These ``linearly polarized chiral phonons'' make it possible to create chiral crystal structures on demand with implications for chiral magnetic and electronic properties.
[1] Juraschek et al., PRResearch, 4, 013129 (2022)
[2] S. Chaudhary, D. M. Juraschek, et al., arXiv:2306.11630 (2023)
[3] J. Luo et al., Science 382, 698 (2023)
[4] T. Kahana, D. A. Bustamante Lopez, and D. M. Juraschek, arXiv:2305.18656 (2023)
[5] C. Romao and D. M. Juraschek, arXiv:2311.00824 (2023)