Probing the Magnetic Ordering of Antiferromagnetic MnPS₃ by Raman Spectroscopy

Ferromagnetic/antiferromagnetic materials are of crucial importance in information storage and spintronics devices. Herein we present a comprehensive study of 2D Heisenberg-like antiferromagnetic material MnPS₃ by optical contrast and Raman spectroscopy. We propose a criterion of 0.1 × ( N - 1) < (Δ R/ R)_max < 0.1 × N ( N ≤ 7) to quickly identify the layer number N by using maximum optical contrast (Δ R/ R)_max of few-layer MnPS₃ on a SiO₂/Si substrate (90 nm thick SiO₂). The Raman modes are also identified by polarization Raman spectroscopy. Furthermore, by temperature-dependent Raman measurements, we obtain three phase transition temperatures of MnPS₃. The transition temperature at around 80 K corresponds to the transition from the antiferromagnetic to paramagnetic phase; the one at around 120 K is related to its second magnetic phase transition temperature due to two-dimensional spin critical fluctuations; the one at around 55 K is associated with unbinding of spin vortices. Our studies provide more evidence to advance knowledge of the magnetic critical dynamics of 2D ferromagnetic/antiferromagnetic systems.