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MA: Fachverband Magnetismus

MA 5: Focus Session: Magnetic Phenomena from Phonon Chirality and Angular Momentum I (joint session MA/TT)

MA 5.7: Talk

Monday, March 17, 2025, 12:30–12:45, H20

Signatures of chiral phonons in MnPS₃ — •Banhi Chatterjee and Peter Kratzer — Faculty of Physics, University of Duisburg-Essen, Lotharstr. 1, 47057, Duisburg, Germany

Chiral phonons can exist in two-dimensional transition metal dichalcogenide (TMDC) monolayers without inversion symmetry. They can be observed in the non-equilibrium state triggered by optical excitations using circularly polarized light. In existing literature a detailed theoretical calculation of the circular phonons production rate has already been done for the TMDC MoS₂. We investigate the antiferromagnetic semiconductor MnPS₃ with a similar hexagonal crystal structure and band-structure like MoS₂ but a larger unit cell as a novel candidate material that may allow for excitation of circular phonons. In MnPS₃, although the total magnetic moment is zero in the ground state, exciting the system using circularly polarized light induces a net magnetic moment. The damping of the magnons observed experimentally points to the transfer of orbital angular moment to combined phonon-magnon excitations. Using DFT+U and density functional perturbation theory (DFPT) we obtain in-plane chiral phonon modes at the valley-points of a monolayer MnPS₃ and for these modes the S atoms make circular motions. We further study the electron-phonon coupling between these chiral phonon modes and the excited electronic states carrying orbital angular momentum, particularly the dominant d-electrons, in order to theoretically investigate the experimentally observed damping of magnons.

Keywords: 2D materials; chiral phonons; antiferromagnet; electron phonon coupling; magnon damping