Tunable High-Temperature Tunneling Magnetoresistance in All-van der Waals Antiferromagnet/Semiconductor/Ferromagnet Junctions

Abstract

Magnetic tunnel junctions (MTJs) are widely applied in spintronic devices for efficient spin detection through the imbalance of spin polarization at the Fermi level. The van der Waals (vdW) property of 2D magnets with atomically flat surfaces and negligible surface roughness greatly facilitates the development of MTJs, primarily in ferromagnets. Here, A-type antiferromagnetism in 2D vdW single-crystal (Fe_0.8Co_0.2)₃GaTe₂ is reported with T_N ≈ 203 K in bulk and ≈ 185 K in 9-nm nanosheets. The metallic nature and out-of-plane magnetic anisotropy make it a suitable candidate for MTJ electrodes. By constructing heterostructures based on (Fe_0.8Co_0.2)₃GaTe₂/WSe₂/Fe₃GaTe₂, a large tunneling magnetoresistance (TMR) ratio of 180% at low temperature is obtained, with the TMR signal persisting at near-room temperature 280 K. Furthermore, the TMR is tunable by the electric field, and the MTJ device operates stably with a low applied bias down to 1 mV (≈0.6 nA), highlighting its potential for energy-efficient spintronic devices. This work opens up new opportunities for 2D antiferromagnetic spintronics and quantum devices.