Topological insulator Bi2Se3 films on rare earth iron garnets and their high-quality interfaces

Abstract

The integration of quantum materials like topological insulators (TIs) with magnetic insulators (MIs) has important technological implications for spintronics and quantum computing. Here, we report excellent crystallinity of c-axis oriented epitaxial TI films of Bi2Se3 grown on MI films, a rare earth iron garnet (ReIG), such as thulium iron garnet (Tm3Fe5O12, TmIG), by molecular beam epitaxy using Se-buffered low-temperature growth technique. Strained-TmIG films with robust perpendicular magnetic anisotropy were deposited by off-axis sputtering. We demonstrated a streaky reflection high-energy electron diffraction pattern starting from the very first quintuple layer of Bi2Se3, indicating the high-quality interface between TmIG and Bi2Se3, a prerequisite for studying interfacial exchange coupling effects. The strong interfacial exchange interaction was manifested by the observation of an anomalous Hall effect in the Bi2Se3/TmIG bilayer and a shift of the ferromagnetic resonance field of TmIG induced by Bi2Se3. We have reproducibly grown high-quality Bi2Se3/ReIG and interfaces using this TI growth method, which may be applied to grow other types of van der Waals hetero-structures.

High-Temperature Anomalous Hall Effect in a Transition Metal Dichalcogenide Ferromagnetic Insulator Heterostructure

“…To our knowledge, this work presents a record high temperature for the observation of AHE in TMDs, and the large R AHE is more than 1 order of magnitude larger than those previously reported in topological insulators or TMD-based heterostructures. − The deposition of ZrTe 2 on YIG yields unexpected extra layers and complicated heterostructure of ZrTe 2 /ZrO 2 /a-YIG:Te/YIG, and as the ZrTe 2 film is adjacent to the ZrO 2 layer, we believe that the ZrO 2 layer plays a crucial role in the observed AHE. In order to prove this hypothesis, we conducted control experiment by making a ZrO 2 layer on LaAlO 3 through oxidation of sputter-deposited Zr metal thin films.…”

“…Zirconium ditelluride (ZrTe 2 ) is a nonmagnetic TMD as well as a candidate for topological materials, showing excellent properties, such as high mobility and large magnetoresistance, that are promising for quantum devices applications. , Thus, introducing magnetism in the TMD ZrTe 2 by the heterostructure approach to a ferromagnetic insulator is rather interesting because the quantum AHE (QAHE) is predicted in the integrated systems of topological materials and ferromagnetic materials . The quantum AHE possesses a dissipationless chiral edge current transport in the absence of an external magnetic field, which promises spintronic applications at the nanoscale. , To date, one of the most important topics in this field is the realization of high-temperature QAHE, − for which the magnetic behavior persisting to high temperatures is an essential prerequisite. In this work, we demonstrate induced magnetism in ZrTe 2 via the heterostructure approach and directly probe the magnetism by measuring the AHE.…”

Optimization of the Growth of the Van der Waals Materials Bi2Se3 and (Bi0.5In0.5)2Se3 by Molecular Beam Epitaxy

“…During the heating, the extra elemental selenium evaporates, and we hypothesize that the small domains of Bi 2 Se 3 will coalesce and form a more complete layer in the (0003) orientation. This method has been tried on rare earth iron garnet substrates like thulium iron garnet …”

“…This method has been tried on rare earth iron garnet substrates like thulium iron garnet. 42 We expected that this particular strategy would be most beneficial on GaAs rather than on sapphire. Because of the unpassivated dangling bonds after deoxidation, the in-plane Bi 2 Se 3 vdW epitaxial growth ((0001) orientation) on GaAs is in competition with the Bi 2 Se 3 out-of-plane traditional epitaxy growth ((101̅ 5) orientation), especially at the early stages of growth as observed in RHEED.…”

“…Bi 2 Se 3 has been successfully grown on many substrates including silicon (Si), , III-Vs like gallium arsenide (GaAs) and indium phosphide (InP), ,, sapphire (α-Al 2 O 3 ), , hexagonal boron nitride (h-BN), graphene, strontium titanium oxide (SrTiO 3 ), , and rare earth iron garnets like yttrium iron garnet (YIG) and thulium iron garnet (TmIG). , For the purposes of this paper, we divided the substrates into two categories: substrates with no dangling bonds, like epi-ready sapphire, or substrates with dangling bonds and/or surface reconstructions, like GaAs. For GaAs substrates used in a III-V system, the surface oxide layer is often thermally removed by heating the substrate to the oxide desorption temperature.…”