Ultrafast laser-induced spin–lattice dynamics in the van der Waals antiferromagnet CoPS3
D. I. Khusyainov, T. T. Gareev, V. Radovskaia, Krishna Sampathkumar, Swagata Acharya, Makars Šiškins, Samuel Mañas‐Valero, B. A. Ivanov, Eugenio Coronado, Th. Rasing, A. V. Kimel, D. Afanasiev
Abstract
CoPS3 stands out in the family of the van der Waals antiferromagnets XPS3 (X = Mn, Ni, Fe, and Co) due to the unquenched orbital momentum of the magnetic Co2+ ions, which is known to facilitate the coupling of spins to both electromagnetic waves and lattice vibrations. Here, using a time-resolved magneto-optical pump–probe technique, we experimentally study the ultrafast laser-induced dynamics of mutually correlated spins and lattice. It is shown that a femtosecond laser pulse acts as an ultrafast heater and, thus, results in the melting of the antiferromagnetic order. At the same time, the resonant pumping of the 4T1g → 4T2g electronic transition in Co2+ ions effectively changes their orbital momentum, giving rise to a mechanical force that moves the ions in the direction parallel to the orientation of their spins, thus generating a coherent Bg phonon mode at the frequency of about 4.7 THz.