Low Temperature Deposition of Magnetic Materials on Topological Materials

n conjunction with ferromagnetic and antiferromagnetic materials the topological insulators are elements of future magnetic random access memory (MRAM) and GHz-to-THz frequency sources (spin-torque nano-oscillators, STNO). One of the major challenges in applying topological insulators (TIs) in magnetic devices is the mutual incompatible deposition processes. TIs are usually destroyed by the high temperatures needed for growing high quality magnetic insulators. Here we propose to utilize low-temperature (<100C)spin spray deposition to deposit high-crystalline quality magnetic (Ni-ferrites, NiZn-ferrites, etc.) and antiferromagnetic (NiO, CoO, etc.) oxides on TIs. Spin-spray deposition has been developed by the principal investigators for depositing different ferrites, ZnO, Al2O3, etc. on various substrates such as Si, SiO2, mica, PCB and others for integrated microwave ferrite devices. Spin spray deposition process will be developed and optimized for high-crystalline quality ferrite/TI and antiferromagnet/TI heterostructures with a clean interface with strong spin-orbit coupling. Extensive characterization will be carried out on the magnetic, electronic, structural and chemical properties, and their relation to spin spay processing conditions, and spin-orbital coupling in ferrite/TI and antiferromagnet/TI heterostructures. Control of magnetic anisotropy, magnetodynamics, and antiferromagnetic Neél order driven by electrical current through the topological insulator will be carried out in spin spray deposited ferrite/TI and antiferromagnet/TI heterostructures.