Excitons and excitonic materials

Abstract

The dynamics of coupled quasiparticle excitations can be crucial for understanding and engineering the novel states of matter, e.g., two-dimensional (2D) magnetic materials. NiPS3 is one of the 2D van der Waals antiferromagnets which host strong correlations between different degrees of freedom, creating new opportunities for potential next-generation device applications. In this study, we have performed temperature, magnetic-field, and polarization-dependent Raman as well as magnetic susceptibility measurements on flakes of NiPS3. Our measurements reveal the presence of magnetic excitation and its coupling with phonons well above the Néel temperature (TN∼155K), at least up to 4⁢TN which is corroborated by the evolution of magnetic correlations observed in the susceptibility data. This coupling is manifested as Fano anomaly in the phonon modes, explained based on energy overlap and symmetry matching of phonons and the magnetic excitation, as it renormalizes across the magnetic transition (TN). This is further supported by the observations made in Zn-doped magnetically diluted NiPS3, suggesting the robustness of its high temperature (𝑇>TN) magnetic state.