Light Control of Magnetism in Quantum Materials

We will discuss light control of magnetism in van der Waals antiferromagnets and oxide interfaces and surfaces, focusing on the role of orbital angular momentum. In the first example, we will consider the control of magnetic ordered states using light. We will show that light-driven phonons can be utilized to coherently manipulate macroscopic magnetic states. Intense mid-infrared electric field pulses, tuned to resonance with a phonon mode of the antiferromagnet DyFeO3, induce ultrafast and long-living changes of the fundamental exchange interaction between rare-earth orbitals and transition metal spins. [1-3]. In the second example we will discuss the emission and detection of a nanometre-scale wavepacket of coherent propagating magnons in the antiferromagnetic oxide dysprosium orthoferrite using ultrashort pulses of light [4]. In the third example we consider experimentally the relative merits of electronic and vibrational excitations for the optical control of zero orbital angular momentum magnets, focusing on a limit case: the antiferromagnet manganese phosphorous trisulfide (MnPS3), constituted by orbital singlet Mn2+ ions. We study the correlation of spins with two types of excitations within its band gap: a bound electron orbital excitation from the singlet orbital ground state of Mn2+ into an orbital triplet state, which causes coherent spin precession, and a vibrational excitation of the crystal field that causes thermal spin disorder [5].<br/><br/><br/>[1] J.R. Hortensius, et al npj Quantum Materials 5, 95 (2020).<br/>[2] D. Afanasiev, et al Nature Materials 20, 607 (2021).<br/>[3] D. Afanasiev, et al Science Advances (2021).<br/>[4] J.R. Hortensius, et al Nature Physics 17, 1001 (2021).<br/>[5] M. Matthiesen, et al Phys. Rev. Lett. 130, 076702 (2023)