We present a mechanism by which circularly driven phonon modes in the rare-earth trihalides generate giant effective magnetic fields acting on the paramagnetic 4f spins. With cerium trichloride (CeCl3) as our model system, we calculate the coherent phonon dynamics in response to the excitation by an ultrashort terahertz pulse using a combination of first-principles calculations and phenomenological modeling. We find that effective magnetic fields of over 100 T can possibly be generated that polarize the spins for experimentally accessible pulse energies. This mechanism potentially creates a way to control the magnetic and electrical order of ferromagnets and ferroelectrics through interfacial coupling with the phonon-induced magnetization in heterostructures.

Last updated on 02/18/2022