Scalar Spin Chiral Order via Bond Selectivity in Strained Collinear Ferrimagnets
Scalar spin chirality (SSC) drives a series of topological transports in noncoplanar magnets. However, the ordering temperature of magnet hosting intrinsic SSC order is typically below 100 K. Current approaches to achieve near room temperature SSC order largely rely on external fields or chemical doping in noncollinear magnets. A significant challenge persists in generating and controlling SSC order in high temperature collinear magnets. Here, using the collinear ferrimagnet Mn4N with Neel temperature ~740 K as a platform, we demonstrate that isotropic strain acts as a clean and continuous tuning parameter to induce long range SSC order by first principles calculations. As strain increases from to, the magnetic ground state evolves continuously from a collinear to a noncoplanar configuration, activating the SSC order and enhancing its magnitude from 0 to ~2.32. Our quantitative orbital-resolved bonding analysis reveals that strain selectively suppresses the bond between Mn 3d orbitals and N 2p orbitals, driving dual prerequisites for the SSC order. Specifically, the decreased covalent spin-pairing activates Mn3c moments within the plane, simultaneously the suppressed N-mediated ferromagnetic superexchange interaction shifts the balance of the nearest-neighbor Mn3c sites toward antiferromagnetic exchange interaction. Our findings establish a powerful strain mediated route to construct the SSC order in high temperature collinear magnets.