Large Room-Temperature Magnetoresistance in van der Waals Ferromagnet/Semiconductor Junctions

Abstract

The magnetic tunnel junction (MTJ) is the core component in memory technologies, such as the magnetic random-access memory, magnetic sensors and programmable logic devices. In particular, MTJs based on two-dimensional (2D) van der Waals (vdW) heterostructures offer unprecedented opportunities for low power consumption and miniaturization of spintronic devices. However, their operation at room temperature remains a challenge. Here, we report a large tunnel magnetoresistance (TMR) of up to 85% at room temperature (T = 300 K) in vdW MTJs based on a thin (< 10 nm) semiconductor spacer WSe2 layer embedded between two Fe3GaTe2 electrodes with intrinsic above-room-temperature ferromagnetism. The TMR in the MTJ increases with decreasing temperature up to 164% at T = 10 K. The demonstration of TMR in ultra-thin MTJs at room-temperature opens a realistic and promising route for next-generation spintronic applications beyond the current state of the art.

Fe3GaTe2/MoSe2 ferromagnet/semiconductor 2D van der Waals heterojunction for room-temperature spin-valve devices

“…49 The MR values decrease with temperature from 2 K to 300 K, which may be due to thermal diffusion of electron energy distribution and impurity scattering. 50 The value of the maximum MR (37.7%) is larger than that of conventional spin-valve devices, such as NiFe/graphene/NiFe (0.48%), Fe 3 GeTe 2 /MoS 2 /Fe 3 GeTe 2 (3.1%), and Fe 3 GaTe 2 /MoS 2 /Fe 3 GaTe 2 (15.9%), 51 but still smaller than that of Fe 3 GaTe 2 /WSe 2 /Fe 3 GaTe 2 tunneling spin-valves (164%), 52 which indicates that the electrons still suffer large spin polarization loss when passing through the MoSe 2 spacer. The performance of spin-valve devices may be improved by optimizing the spacer layer.…”

Room-temperature spin-valve devices based on Fe3GaTe2/MoS2/Fe3GaTe2 2D van der Waals heterojunctions

“…5c; the P value decreased from 27% to 4% as the temperature was increased from 2.3 K to 300 K, which is higher than that observed in other MoS 2 -based spin-valve devices. However, compared with heterojunctions that are based on the tunneling effect, such as Fe 3 GeTe 2 /InSe/Fe 3 GeTe 2 , 49 Fe 3 GeTe 2 /BN/Fe 3 GeTe 2 , 18 and Fe 3 GaTe 2 /WSe 2 /Fe 3 GaTe 2 , 50 this value is still relatively low due to the spin-polarization loss in Fe 3 GaTe 2 when the electrons cross through the MoS 2 spacer, which can be further improved by replacing the spacer layer with wide-bandgap semiconductors or insulators. The temperature-dependence of P was fitted based on the Bloch law 51 using the equation P ( T ) = P (0)(1 − αT 3/2 ), where P (0) refers to the spin polarization at 0 K, and α is a material-dependent constant.…”

“…58 Some discussions can be referred between these two published versions. During the publication of this work, we also published our collaborated work using WSe 2 as spacer 50 and our another work using MoSe 2 spacer. 59 4.…”

Nonlocal Spin Valves Based on Graphene/Fe3GeTe2 van der Waals Heterostructures

“…The tunnel magnetoresistance of up to 85% has been realized in Fe 3 GaTe 2 /WSe 2 /Fe 3 GaTe 2 heterostructures at room temperature. 40 In addition, 2D Fe 5 GeTe 2 and cobalt have been employed to fabricate NLSVs at room temperature. 41 However, whether an all-2D vdWs NLSV can be fabricated and more importantly whether their performance can be improved by the high-quality interfaces have not been investigated yet.…”

“…Recently, 2D vdWs ferromagnetic metals, Fe 5 GeTe 2 and Fe 3 GaTe 2 , with the Curie temperature near or above room temperature have been discovered. The tunnel magnetoresistance of up to 85% has been realized in Fe 3 GaTe 2 /WSe 2 /Fe 3 GaTe 2 heterostructures at room temperature . In addition, 2D Fe 5 GeTe 2 and cobalt have been employed to fabricate NLSVs at room temperature .…”