Magnetic tunnel junctions (MTJs) with conventional bulk ferromagnets separated by a nonmagnetic insulating layer are key building blocks in spintronics for magnetic sensors and memory. A radically different approach of using atomically-thin van der Waals (vdW) materials in MTJs is expected to boost their figure of merit, the tunneling magnetoresistance (TMR), while relaxing the lattice-matching requirements from the epitaxial growth and supporting high-quality integration of dissimilar materials with atomically-sharp interfaces. We report TMR up to 192% at 10 K in all-vdW Fe3GeTe2/GaSe/Fe3GeTe2 MTJs. Remarkably, instead of the usual insulating spacer, this large TMR is realized with a vdW semiconductor GaSe. Integration of two-dimensional ferromagnets in semiconductor-based vdW junctions offers gate-tunability, bias dependence, magnetic proximity effects, and spin-dependent optical-selection rules. We demonstrate that not just the magnitude, but also the TMR sign is tuned by the applied bias or the semiconductor thickness, enabling modulation of highly spin-polarized carriers in vdW semiconductors.
@article{arxiv.2303.11596,
title = {Large and tunable magnetoresistance in van der Waals Ferromagnet/Semiconductor junctions},
author = {Wenkai Zhu and Yingmei Zhu and Tong Zhou and Xianpeng Zhang and Hailong Lin and Qirui Cui and Faguang Yan and Ziao Wang and Yongcheng Deng and Hongxin Yang and Lixia Zhao and Igor Žutić and Kirill D. Belashchenko and Kaiyou Wang},
journal= {arXiv preprint arXiv:2303.11596},
year = {2023}
}