Design of altermagnetism in oxide superlattices exploiting interface effects and quantum confinement

Abstract

The discovery of altermagnetism has initiated intensive research and opened new avenues for spin- tronic and transport applications. While current efforts are mostly focused on bulk materials which are typically insulating, here we propose design strategies to achieve a combination of altermag- netism and metallicity in oxide superlattices by exploiting symmetry breaking, electrostatic doping and confinement. While bulk SrCrO3 does not exhibit altermagnetism due to compensating effects between adjacent layers our density functional theory calculations with a Hubbard U parameter re- veal, that a single SrCrO3 layer confined in a (SrCrO3)1/(SrTiO3)1(001) superlattice (SL) exhibits a sizable non-relativistic spin splitting (NRSS) up to 350 meV with bulk d-wave nature due to the coexistence of orbital ordering and octahedral rotations (OORs). Since this system is insulating, we extend to SrCrO3/LaCrO3(001) SLs. In the (SrCrO3)4/(LaCrO3)4(001) SL the combination of a polar discontinuity at the interface and stronger OORs promotes metallic d-wave altermagnetism. The NRSS of up to 120 meV is contributed by the interfacial Cr d bands at the Fermi level with indications for a spin-selective Fermi surface nesting. These findings establish oxide superlattices as a promising platform to realize and explore altermagnetism for quantum transport and spintronic functionalities