Terahertz field-induced giant symmetry modulations in a van der Waals antiferromagnet
Sheikh Rubaiat Ul Haque, Martin J. Cross, Sangeeta Rajpurohit, Jonah B. Haber, Christopher J. Ciccarino, Alexandra C. Zimmerman, Isabelle J. Sealey, Vadym Kulichenko, Monique Tie, Huaiyu Wang, Sharon S. Philip, Choongwon Seo, Jake D. Koralek, Luis Balicas, Mykhaylo Ozerov, Dmitry Smirnov, Liang Z. Tan, Felipe H. da Jornada, Tadashi Ogitsu, Matthias C. Hoffmann, Tony F. Heinz, Aaron M. Lindenberg
公開日: 2025/10/1
Abstract
Strong-field terahertz (THz) excitations enable dynamic control over electronic, lattice and symmetry degrees of freedom in quantum materials. Here, we uncover pronounced terahertz-induced symmetry modulations and coherent phonon dynamics in the van der Waals antiferromagnet MnPS3, in which inversion symmetry is broken by its antiferromagnetic spin configuration. Time-resolved second harmonic generation measurements reveal long-lived giant oscillations in the antiferromagnetic phase, with amplitudes comparable to the equilibrium signal, driven by phonons involving percent-level atomic displacements relative to the equilibrium bond lengths. The temporal evolution of the rotational anisotropy patterns indicate a dynamic breaking of mirror symmetry, modulated by two vibrational modes at 1.7 THz and 4.5 THz, with the former corresponding to a hidden mode not observed in equilibrium spectroscopy. We show that these effects arise in part from a field-induced charge rearrangement mechanism that lowers the local crystal symmetry, and couples to the phonon modes. A long-lived field-driven response was uncovered with a complex THz polarization dependence which, in comparison to theory, indicates evidence for an antiferromagnetic-to-ferrimagnetic transition. Our results establish an effective field-tunable pathway for driving excitations otherwise weak in equilibrium, and for manipulating magnetism in low-dimensional materials via dynamical modulation of symmetry.