  The behavior of 2-dimensional (2D) van der Waals (vdW) layered magnetic
materials in the 2D limit of the few-layer thickness is an important
fundamental issue for the understanding of the magnetic ordering in lower
dimensions. The antiferromagnetic transition temperature TN of the
Heisenberg-type 2D magnetic vdW material MnPS3 was estimated as a function of
the number of layers. The antiferromagnetic transition was identified by
temperature-dependent Raman spectroscopy, from the broadening of a phonon peak
at 155 cm-1, accompanied by an abrupt redshift and an increase of its spectral
weight. TN is found to decrease only slightly from ~78 K for bulk to ~ 66 K for
3L. The small reduction of TN in thin MnPS3 approaching the 2D limit implies
that the interlayer vdW interaction is playing an important role in stabilizing
magnetic ordering in layered magnetic materials.
