STM study of antiferromagnetic van der Waals materials

Abstract

Magnetic van der Waals (vdW) materials offer a unique opportunity to explore strongly correlated electron systems in the 2D limit. In particular, NiPS3 is antiferromagnetic below the Néel temperature (TN) of 150K, which has many-body exciton states originated from Zhang-Rice singlet. In case of CrPS4 below TN ~ 36K, the A-type antiferromagnetism is energetically most favorable in the ground state, which transforms to ferromagnetic ordering in single-layer limit. However, experimental result on local magnetic structure that would be indispensable for studying the magnetism of these materials at the atomic scale is still lacking. Here we directly measure the atomic and electronic structures native to the surface of antiferromagnetic vdW materials NiPS3 and CrPS4 by scanning tunneling microscopy and spectroscopy. Our result pave the way for the exploration of various spin structure observed in magnetic vdW materials.