Barrier-thickness-engineered giant magnetotransport and multi-level storage in a CrTe2/Al2S3 van der Waals multiferroic junction

Abstract

van der Waals multiferroic tunnel junctions (MFTJs), which combine tunnel magnetoresistance (TMR) and tunnel electroresistance (TER) effects, are promising building blocks for next-generation, low-power non-volatile memory. In this work, we propose a two-dimensional MFTJ based on a CrTe₂/Al₂S₃/CrTe₂ heterostructure and investigate its spin-polarized transport properties using first-principles density functional theory (DFT) with the non-equilibrium Green's function (NEGF) method. By independently controlling the ferroelectric polarization of the Al₂S₃ barrier and the magnetization of the CrTe₂ electrodes, the junction can be switched between multiple non-volatile resistance states. We demonstrate that increasing the barrier thickness from monolayer to bilayer Al₂S₃ dramatically enhances device performance: the TER ratio increases from 24.8% to 3912%, and the TMR ratio rises from 9.8% to 124.7%. Furthermore, the bilayer barrier MFTJ exhibits six distinct resistance states, enabling multi-level data storage. Under finite bias, the device also manifests a significant spin-filtering effect and a negative differential resistance (NDR) effect. These results highlight the strong potential of the CrTe₂/Al₂S₃/Al₂S₃/CrTe₂ MFTJ for advanced spintronic and multi-state memory applications.