Fig. 4: Spin-phonon coupling.
a–d Vibrational modes of MnPSe3 as calculated by DFT for (a) P4, (b) P5, (c) P6, and (d) P7. Manganese atoms are shown as light and dark blue solid spheres, highlighting the alternating spin states, phosphorus atoms are brown spheres, and selenium are yellow spheres. Arrows represent the atomic shifts (from equilibrium) e–l Temperature dependent Raman shift of (e–h) Bulk and (i–l) few layer MnPSe3, with emphasis on the transition from an ordered antiferromagnetic state (blue shaded region) to a disordered paramagnetic state (Red shaded region) about the Néel Temperature (dotted grey line) at 74 K. Black circles show the experimental data with errors associated with peak fitting, while the calculated spin-phonon coupling and anharmonic phonon dependencies are shown in orange and purple solid lines, respectively. The extracted frequency perturbation, Δω, and strength of the spin-phonon coupling, λ, is given for each Raman mode. Error bars are formed from a combination of ± 1σ std. dev. from Voigt curve fitting and ± 0.25*CCD spectral resolution.
