A group of researchers who are a part of an RMIT-led multinational collaboration, recently reported that they have for the first time observed the electronic gate-controlled exchange-bias effect in Van der Waal heterostructures, which have the potential to offer a promising platform for energy-efficient and beyond CMOS electronics. The FLEET-led collaboration of researchers working on potential beyond CMOS electronics, at RMIT University (Australia) and South China University of Technology (China) were able to confirm for the first time the electric control of the EB effect in a vdW heterostructure.
“We had obtained much experience in vdW heterostructure-based nano-devices and we decided it was time for us to utilise some methods, such as electric gates, to control magnetic properties in FM/AFM bilayers,” said the study’s first author, FLEET Research Fellow Dr Sultan Albarakati (RMIT).
“Moreover, we are familiar with proton intercalation, which is an effective tool for modulating materials’ charge density.”
“The choice of FM layer was a bit tricky,” conceded co-author Dr Cheng Tan (RMIT). “Based on our previous results, the EB effect could occur in proton-intercalated Fe3GeTe2, while in Fe5GeTe2 (F5GT) of various thicknesses, the proton intercalation cannot result in any EB effects. Hence, we choose F5GT as the FM layer.”
“Our experimental observations are consistent with this,” said co-author Dr Guolin Zheng (RMIT). “There is no occurrence of EB effects when the thickness of F5GT is less than 10 nm. Luckily, after many tests, we find that the EB effect can survive in FPS-F5GT heterointerfaces when the thickness of F5GT layer is within the range of 12 nm to 20 nm. Then we could further explore the effects of proton intercalations in FPS-F5GT.”
“The blocking temperature of the EB effect can be effectively tuned via electric gate. And more interestingly, the EB field can be switched ‘ON’ and ‘OFF’ repeatably under various gate voltages,” said Guolin.
“The gate-dependent EB effects can be well-explained based on our calculations,” said contributing-author A/Prof Lan Wang (also at RMIT). “Under different proton intercalations, the affected AFM-FM coupling-induced unidirectional anisotropy energy and the transformation of FPS3 between an uncompensated AFM and a compensated AFM lead to the various interesting phenomena.”
“Again, this study is a significant step towards vdW heterostructure-based magnetic logic for future low-energy electronics.”