Large and tunable magnetoresistance in van der Waals ferromagnet/semiconductor junctions

• Published in: Nature communications Vol. 14; no. 1; p. 5371
• Main Authors: Zhu, Wenkai, Zhu, Yingmei, Zhou, Tong, Zhang, Xianpeng, Lin, Hailong, Cui, Qirui, Yan, Faguang, Wang, Ziao, Deng, Yongcheng, Yang, Hongxin, Zhao, Lixia, Žutić, Igor, Belashchenko, Kirill D., Wang, Kaiyou
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 04-09-2023; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/357/1018; 639/766/119/1001; Bias; Dissimilar materials; Epitaxial growth; Ferromagnetism; Figure of merit; Gallium selenides; Heterostructures; Humanities and Social Sciences; Lattice matching; Magnetoresistance; Magnetoresistivity; multidisciplinary; Science; Science (multidisciplinary); Semiconductor junctions; Semiconductors; Spintronics; Thickness; Tunnel junctions; Van der Waals forces
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-41077-0

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 Fe
3
GeTe
2
/GaSe/Fe
3
GeTe
2
MTJs. Remarkably, instead of the usual insulating spacer, this large TMR is realized with a vdW semiconductor GaSe. Integration of semiconductors into the MTJs offers energy-band-tunability, bias dependence, magnetic proximity effects, and spin-dependent optical-selection rules. We demonstrate that not only the magnitude of the TMR is tuned by the semiconductor thickness but also the TMR sign can be reversed by varying the bias voltages, enabling modulation of highly spin-polarized carriers in vdW semiconductors.
Van der Waals materials are composed of layers held weakly by van der Waals forces. This feature allows different materials to be combined into heterostructures, with fewer restrictions on growth and lattice matching. Here, Zhu et al make use of this feature to create a van der Waals magnetic tunnel junction with a semiconducting spacer, allowing for improved tunability and reduced device thickness.