Antiferromagnetic ordering in van der Waals two-dimensional magnetic material MnPS3 probed by Raman spectroscopy

TL;DR

This study uses Raman spectroscopy to investigate magnetic ordering in two-dimensional MnPS3, revealing stable antiferromagnetic order down to bilayer thickness and providing insights into 2D Heisenberg-type antiferromagnets.

Contribution

First demonstration of magnetic ordering in 2D Heisenberg-type MnPS3 using Raman spectroscopy from bulk to bilayer.

Findings

Raman peak at ~155 cm-1 broadens near Néel temperature in bulk

Peak exhibits red-shift at low temperatures in few-layer MnPS3

Magnetic order remains stable down to bilayer thickness

Abstract

Magnetic ordering in the two-dimensional limit has been one of the most important issues in condensed matter physics for the past several decades. The recent discovery of new magnetic van der Waals materials heralds a much-needed easy route for the studies of two-dimensional magnetism: the thickness dependence of the magnetic ordering has been examined by using Ising- and XXZ-type magnetic van der Waals materials. Here, we investigated the magnetic ordering of MnPS3, a two-dimensional antiferromagnetic material of Heisenberg-type, by Raman spectroscopy from bulk all the way down to bilayer. The phonon modes that involve the vibrations of Mn ions exhibit characteristic changes as the temperature gets lowered through the N\'eel temperature. In bulk MnPS3, the Raman peak at ~155 cm-1 becomes considerably broadened near the N\'eel temperature and upon further cooling is subsequently red-shifted. The measured peak positions and polarization dependences of the Raman spectra are in excellent agreement with our first-principles calculations. In few-layer MnPS3, the peak at ~155 cm-1 exhibits the characteristic red-shift at low temperatures down to the bilayer, indicating that the magnetic ordering is surprisingly stable at such a thin limit. Our work sheds light on the hitherto unexplored magnetic ordering in the Heisenberg-type antiferromagnetic systems in the atomic-layer limit.