Exciton-magnon structure of the optical absorption spectrum of antiferromagnetic MnPS3

Abstract

In the region of the A1g6(S6)→A1g4,Eg4(G4) optical transition, the absorption spectrum of the quasi-two-dimensional antiferromagnet MnPS3 has an exciton-magnon structure. It includes a pure exciton line with a wave number of 21223.5cm−1 and an exciton-magnon band with a peak at 21328cm−1 for T=1.7K. The spectra are studied at temperatures ranging from 1.7to80K and with external magnetic fields up to 60kOe. In a magnetic field oriented along the easy axis z, splitting of the exciton line is observed owing to the nonequivalence of the magnetic sublattices with respect to an external field. The behavior of the split components in the region of the spin-orientation transition (35–41kOe) is typical of second order phase transitions.