Investigation of epitaxial SOT heterostructures for energy efficient memory devices​

An existing challenge for realizing a mature low-power, high-speed spin-orbit torque magnetic random-access memory (SOT-MRAM) technology, is to find SOT materials with high SOT-efficiency or high spin-Hall angle (SHA). Different classes of SOT materials, such as heavy metals, topological materials, orbital Hall effect (OHE) configurations, etc. have been being explored. Among these OHE is emerging as a promising candidate generating substantial transverse orbital angular momentum in the weak spin-orbit coupling materials [1], [2] . This feature opens up a research domain on a broad and most importantly industry compatible SOT heterostructures comprising light elements like Cr, Ru, Ti etc. for energy efficient next generation spin-orbitronic devices. Moreover, exploring epitaxial routes to (a) grow defect free SOT material, (b) efficient orbital transport through precisely controlled crystallographic orientation, atomically sharp interfaces[3] , and (c) efficient conversion of orbital current to spin current[4]  for the development of energy efficient magnetic memory device, demands urgent research attention from scientific communities.

This internship topic will focus on (a) investigation of the structural (by XRD or HRTEM) & magnetic properties (by VSM/MOKE) of epitaxially grown orbital heterostructures, (b) the orbital current generation and transport; orbital to spin conversion and SOT efficiency characterization (by high harmonic Hall set up and loop shift set-up) on a few epitaxial SOT heterostructures. The primary goal is to build deeper understanding on correlation of spin-orbit torque efficiency with the crystallinity of epitaxial structures to reduce the switching current of SOT-MRAM devices

Motivated students with inquisitive, critical thinking and analytical mindset are highly encouraged for this position. The student should have a strong interest in doing extensive literature surveys to find potentially interesting epitaxial heterostructures, knowledge on spintronics and nano-magnetism. Existing skills on SOT characterization and analysis will be advantageous for this project.

[1]    [1] D. Lee et al., “Orbital torque in magnetic bilayers,” Nat. Commun., vol. 12, no. 1, Dec. 2021, doi: 10.1038/s41467-021-26650-9.

[2]    [2] R. Gupta et al., “Harnessing orbital Hall effect in spin-orbit torque MRAM,” Nature Communications , vol. 16, no. 1, Dec. 2025, doi: 10.1038/s41467-024-55437-x.

[3]    [3] H. Hayashi et al., “Crystallographic Engineering for Enhanced Orbital Torque,” Nano Lett., vol. 25, no. 41, pp. 15124–15129, Oct. 2025, doi: 10.1021/acs.nanolett.5c04272.

[4]    [4] G. Sala and P. Gambardella, “Giant orbital Hall effect and orbital-to-spin conversion in 3d, 5d, and 4f metallic heterostructures,” Phys. Rev. Res., vol. 4, no. 3, Jul. 2022, doi: 10.1103/PhysRevResearch.4.033037.