Interface Engineering Enabled Low Temperature Growth of Magnetic Insulator on Topological Insulator. Issue 35 (21st October 2022)

• Record Type: Journal Article
• Authors: Bhattacharjee, Nirjhar; Mahalingam, Krishnamurthy; Will‐Cole, Alexandria; Wei, Yuyi; Fedorko, Adrian; Bowers, Cynthia T.; Page, Michael; McConney, Michael; Heiman, Don; Sun, Nian Xiang
• Is Part Of: Advanced materials interfaces. Volume 9:Issue 35(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-10-21
• Subjects: ferromagnets -- interfaces -- magnetic topological insulators -- topological insulators -- van der Waals materials; Materials science -- Periodicals; 620.11
• DOI: 10.1002/admi.202201691
• Languages: English
• ISSNs: 2196-7350

Abstract

Abstract: Combining topological insulators (TIs) and magnetic materials in heterostructures is crucial for advancing spin‐based electronics. Magnetic insulators (MIs) can be deposited on TIs using the spin‐spray process, which is a unique nonvacuum, low‐temperature growth process. TIs have highly reactive surfaces that oxidize upon exposure to atmosphere, making it challenging to grow spin‐spray ferrites on TIs. In this work, it is demonstrated that a thin titanium capping layer on TI, followed by oxidation in atmosphere to produce a thin TiOx interfacial layer, protects the TI surface, without significantly compromising spin transport from the magnetic material across the TiOx to the TI surface states. First, it is demonstrated that in Bi2 Te3 /TiOx /Ni80 Fe20 heterostructures, TiOx provides an excellent barrier against diffusion of magnetic species, yet maintains a large spin‐pumping effect. Second, the TiOx is also used as a protective capping layer on Bi2 Te3, followed by the spin‐spray growth of the MI, Nix Zny Fe2 O4 (NZFO). For the thinnest TiOx barriers, Bi2 Te3 /TiOx /NZFO samples have antiferromagnetic (AFM) disordered interfacial layer because of diffusion. With increasing TiOx barrier thickness, the diffusion is reduced, but still maintains strong interfacial magnetic exchange‐interaction. These experimental results demonstrate a novel method of low‐temperature growth of magnetic insulators on TIs enabled by interface engineering. Abstract : Topological insulators (TIs) are unstable at high temperatures and have highly reactive surfaces. This makes growth of magnetic insulators (MIs) on TIs a significant engineering challenge. In this work, low‐temperature growth of MI, NiZn‐Ferrite (NZFO) using spin‐spray process is demonstrated on TI, Bi2 Te3 capped with thin layers of TiOx . The interface engineered TI/TiOx /MI heterostructures show finite interfacial magnetic interactions without degrading the TI surface.