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 (Fe0.8Co0.2)3GaTe2 is reported with TN ≈ 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 (Fe0.8Co0.2)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.

Tuning the magnetic properties of van der Waals Fe3GaTe2 crystals by Co doping

“…However, this induction simultaneously alters the magnetic anisotropy of the obtained antiferromagnetic materials to the easy plane, rendering them unsuitable for vertically stacked heterostructures in MTJs. 16 The FGaT with large perpendicular magnetic anisotropy and high Tc is promising to address these challenges. Various methods, including electric-field, [17][18][19] strain, 20 doping, [21][22][23][24][25] and proximity effects, 26,27 have been employed to investigate RT 2D ferromagnets and antiferromagnets.…”

“…23 Similarly, A-type antiferromagnetism in (Fe 0.8 Co 0.2 ) 3 GaTe 2 has been observed, with T N values of approximately 203 K in bulk and 185 K in 9-nm-thick nanosheets during the submission of this paper. 16 Additionally, it has been reported that Ni with x = 0.03 substituting for Fe in (Fe 1− x Ni x ) 3 GaTe 2 crystals can enhance the coercive field ( H C ) up to ∼200% while maintaining the ferromagnetic state at room temperature. 28 Despite these findings, there are still very few studies on substitutional doping of FGaT, especially on tuning antiferromagnetism.…”