2026/07/17 by Zhi Yan, Yuwen Hua, Yueting Li +3
#cond-mat.mtrl-sci
Altermagnets enable spin-split transport without stray magnetic fields, yet converting their momentum-dependent spin splitting into a strong tunnel-junction response requires interface-selected tunneling channels. Here, using density functional theory combined with nonequilibrium Green's function calculations, we demonstrate giant multistate resistance switching in CrSb/α-In2Se3 altermagnetic multiferroic tunnel junctions. The response is governed not by the bulk spin splitting of CrSb alone, but by a symmetry-selected interfacial mechanism in which Cr/Sb terminations and h-BN or graphene insertion layers determine spin-channel matching, while ferroelectric polarization reshapes the electrostatic barrier. Symmetric and asymmetric terminations reverse the correspondence between parallel/antiparallel Néel-vector configurations and high-/low-resistance states, showing that the actual alignment of interfacial Cr moments selects the dominant tunneling channels. Monolayer-In2Se3 junctions exhibit four nonvolatile resistance states, with tunneling magnetoresistance (TMR) and tunneling electroresistance (TER) reaching 1626% and 2206%, respectively, and increasing to 9576% and 4144% upon Fermi-level shifting. Finite-bias calculations further reveal robust spin filtering and tunable spin-polarized currents. Extending the barrier to bilayer In2Se3 introduces interlayer polarization coupling, enabling eight resistance states with maximum TMR and TER values of 3.77×104% and 4.18×105%, respectively. These results establish interface symmetry, spin-channel matching, and ferroelectric barrier reconstruction as design principles for stray-field-free multistate spintronic tunnel devices.