Researchers discover new spintronics mode in 2D heterostructure

"We discovered a previously unseen mode of giant magneto-resistance (GMR) in the material."Sultan Albarakati, RMIT University

A theoretical-experimental collaboration across two nodes of the ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET) has discovered new magnetic properties in two-dimensional (2D) structures. This finding, reported in a paper in Science Advances, has exciting potential for researchers in the emerging field of 'spintronics'.

Spintronic devices use a quantum electron property known as 'spin', in addition to the electronic charge of conventional electronics. Spintronics promises ultra-high-speed, low-energy electronic devices with significantly enhanced functionality.

In this study, researchers at RMIT University and the University of New South Wales (UNSW), both in Australia, together with colleagues in China and Korea, discovered never-before-seen magnetic properties in devices known as vdW heterostructures, which comprise several layers of novel 2D materials. These latest results show that vdW spintronics could produce devices with more functionality, compared with traditional spintronic approaches. Further research could generate devices with significant industrial applications.

Two-dimensional ferromagnetic van-der-Waals (vdW) materials have recently emerged as effective building blocks for a new generation of 'spintronic' devices. When layered with non-magnetic vdW materials such as graphene and topological insulators, vdW heterostructures can be assembled to provide otherwise unattainable device structures and functionalities.

The RMIT and UNSW researchers were studying the 2D material Fe₃GeTe₂ (FGT), a metal found to display promising ferromagnetic properties for spintronic devices in a previous FLEET study. "We discovered a previously unseen mode of giant magneto-resistance (GMR) in the material," says co-author Sultan Albarakati from RMIT University.

Unlike the two previously known GMR states (high resistance and low resistance) that occur in thin-film heterostructures, the researchers measured antisymmetric GMR with an additional, distinct, intermediate resistance state. "This reveals that vdW ferromagnetic heterostructures exhibit substantially different properties from similar structures," says Sultan.

This surprising result is contrary to previously held beliefs regarding GMR. It suggests different underlying physical mechanisms in vdW heterostructures, with potential for improved magnetic information storage. Theoretical calculations indicate that the three levels of resistance are the result of a spin-momentum-locking-induced spin-polarized current at the graphite/FGT interface.

"This work has significant interest for researchers in 2D materials, spintronics and magnetism," says co-author Cheng Tan from RMIT University. "It means that 'traditional' tunnelling magnetoresistance devices, spin-orbit torque devices and spin transistors may reward re-investigation using similar vdW heterostructures to reveal similarly surprising characteristics."

This story is adapted from material from FLEET, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.