Phonon and Thermal Properties of Quasi-Two-Dimensional FePS₃ and MnPS₃ Antiferromagnetic Semiconductors.

Abstract

We report results of investigation of the phonon and thermal properties of the exfoliated films of layered single crystals of antiferromagnetic FePS₃ and MnPS₃ semiconductors. Raman spectroscopy was conducted using three different excitation lasers with wavelengths of 325 nm (UV), 488 nm (blue), and 633 nm (red). UV-Raman spectroscopy reveals spectral features which are not detectable <i>via</i> visible Raman light scattering. The thermal conductivity of FePS₃ and MnPS₃ thin films was measured by two different techniques: the steady-state Raman optothermal and transient time-resolved magneto-optical Kerr effect. The Raman optothermal measurements provided the orientation-average thermal conductivity of FePS₃ to be 1.35 ± 0.32 W m^-1 K^-1 at room temperature. The transient measurements revealed that the through-plane and in-plane thermal conductivity of FePS₃ are 0.85 ± 0.15 and 2.7 ± 0.3 W m^-1 K^-1, respectively. The films of MnPS₃ have higher thermal conductivity of 1.1 ± 0.2 W m^-1 K^-1 through-plane and 6.3 ± 1.7 W m^-1 K^-1 in-plane. The data obtained by the two techniques are in agreement and reveal strong thermal anisotropy of the films and the dominance of phonon contribution to heat conduction. The obtained results are important for the interpretation of electric switching experiments with antiferromagnetic materials as well as for the proposed applications of the antiferromagnetic semiconductors in spintronic devices.