SP-STM study of layered magnetic material Fe3GeTe2

2D magnets have attracted great research interest due to their great potentials for spintronic application. With this regard, magnetic layered 2D materials have offered great opportunities for creating exfoliated 2D magnets. Here we report a recent study on magnetic 2D materials of Fe3GeTe2 cleaved in situ under ultra-high vacuum (UHV) using Variable-Temperature Spin-Polarized Scanning Tunneling Microscopy (VT-SP-STM). Atomic resolution images and scanning tunneling spectroscopy are acquired with both non-magnetic (W) tips and ferromagnetic (Ni) tips. Interestingly, two kinds of magnetic domain structure are observed at liquid nitrogen temperature. These domains show temperature-dependent magnetic phase transitions at \textasciitilde 180 K and \textasciitilde 250 K, respectively, which are further corroborated by SQUID magnetometry measurements. The microscopic origins of these transition will be discussed. This research was conducted at the Center for Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laboratory by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy.