Above-room-temperature multiferroic tunnel junction with altermagnetic CrSb

Abstract: Altermagnets with non-relativistic momentum-dependent spin splitting and compensated net magnetic moments have recently garnered significant interest in spintronics, particularly as pinning layers in magnetic tunnel junctions (MTJs). However, room-temperature (RT) altermagnet-based MTJs with tunable tunneling magnetoresistance (TMR) or electroresistance (TER) modulated by multiferroicity remains largely unexplored. Here, we propose an experimentally fabricable above-RT multiferroic MTJ, comprising an altermagnetic metal, ferroelectric barrier, and ferromagnetic metal-epitomized by a CrSb/In2Se3/Fe3GaTe2 heterostructure. Our calculations with first-principles and nonequilibrium Green function method indicate that the architecture enables magnetically switchable TER, electrically tunable TMR, and dual-mode controllable spin filtering. To disentangle the roles of ferroelectricity and the tunnel barrier, non-ferroelectric Sb2Se3 and a vacuum gap are exploited as control cases. Remarkably, the system achieves TMR up to 2308 %, TER of 707 %, and near-perfect spin filtering efficiency. Both TMR and TER are considerable for CrSb/In2Se3/Fe3GaTe2 with either Cr or Sb interface. These findings demonstrate the above-RT multiferroic altermagnet-based MTJs and highlight their exciting potential as a versatile platform for next-generation spin dynamics, magnetic-sensing and quantum logic nano-devices.