Mike Pols
Angular momentum is an often overlooked degree of freedom in crystals, carried not only by electrons but also by lattice vibrations. Using first-principles simulations, I will show how phonons provide a route to generate and control angular momentum in crystals under thermal and optical driving. First, I will focus on chiral two-dimensional halide perovskites, in which phonons carry angular momentum [1], and show how their chemical composition can strongly influence the magnitude and character of the generated angular momentum [2]. Next, I will shift to oxide perovskites, in which the circular excitation of optical phonons can also generate angular momentum within the crystal lattice. By tuning the polarization of the excitation, and thus the amount of angular momentum, it becomes possible to create multiferrons, a new type of quasiparticle carrying finite polarization and magnetization [3].
[1] [2] [3] M. Pols, G. Brocks, S. Calero, and S. Tao, Nano Lett. 25, 10003 (2025).
M. Pols, H. Boom, G. Brocks, S. Calero, and S. Tao, Phys. Rev. Mater. 9, 113601 (2025).
M. Pols, C. P. Romao, and D. M. Juraschek, arXiv:2510.15703, 10.48550/arXiv.2510.15703 (2025).