Scanning Tunneling Microscopy Study of Epitaxial Fe3GeTe2 Monolayers on Bi2Te3

Abstract

Introducing magnetism to the surface state of topological insulators, such as Bi2Te3, can lead to a variety of interesting phenomena. We use scanning tunneling microscopy (STM) to study a single quintuple layer (QL) of the van der Waals magnet Fe3GeTe2 (FGT) that is grown on Bi2Te3 via molecular beam epitaxy. STM topographic images show that the FGT grows as free-standing islands on Bi2Te3 and outwards from Bi2Te3 steps. Atomic resolution imaging shows atomic lattices of 390 +- 10 pm for FGT and 430 +- 10 pm for Bi2Te3, consistent with the respective bulk crystals. A moiré pattern is observed on FGT regions with a periodicity of 4.3 +- 0.4 nm that can be attributed solely to this lattice mismatch and thus indicates zero rotational misalignments. While most of the surface is covered by a single QL of the FGT, there are small double QL regions, as well as regions with distinct chemical terminations due to an incomplete QL. The most common partial QL surface termination is the FeGe layer, in which the top two atomic layers are missing. This termination has a distinctive electronic structure and a (sqrt3 x sqrt3)R30 reconstruction overlaid on the moiré pattern in STM images. Magnetic circular dichroism (MCD) measurements confirm these thin FGT films are ferromagnetic with TC ~190 K.

arXiv comment12 pages, 5 figures

References in corpus (21)

• Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
• Gate-tunable Room-temperature Ferromagnetism in Two-dimensional Fe${}_3$GeTe${}_2$
• Two-Dimensional Itinerant Ising Ferromagnetism in Atomically thin Fe3GeTe2
• Experimental demonstration of the topological surface states protected by the time-reversal symmetry
• STM imaging of electronic waves on the surface of Bi${}_2$Te${}_3$: topologically protected surface states and hexagonal warping effects
• Weyl semimetal with broken time reversal and inversion symmetries
• Néel-type skyrmion in WTe2/Fe3GeTe2 van der Waals heterostructure
• Layer Hall effect in a 2D topological Axion antiferromagnet
• Skyrmions in the moiré of van der Waals 2D magnets
• Highly efficient spin-orbit torque and switching of layered ferromagnet Fe3GeTe2
• Néel-type skyrmions and their current-induced motion in van der Waals ferromagnet-based heterostructures
• Mixed topological semimetals driven by orbital complexity in two-dimensional ferromagnets
• Kondo holes in the 2D itinerant Ising ferromagnet Fe3GeTe2
• Bulk Cr tips for scanning tunneling microscopy and spin-polarized scanning tunneling microscopy
• Large magneto-optical effect and magnetic anisotropy energy in two-dimensional metallic ferromagnet Fe${}_3$GeTe${}_2$
• Magnetic domain walls of the van der Waals material Fe${}_3$GeTe${}_2$
• Tuning the Curie temperature of a 2D magnet/topological insulator heterostructure to above room temperature by epitaxial growth
• Topological insulator ring with magnetic impurities
• Field-free deterministic switching of a perpendicularly polarized magnet using unconventional spin-orbit torques in WTe2
• Kinetically-controlled epitaxial growth of Fe${}_3$GeTe${}_2$ van der Waals ferromagnetic films
• Room temperature energy-efficient spin-orbit torque switching in wafer-scale all-vdW heterostructure