Tuning spin currents in collinear antiferromagnets and altermagnets

Spin-current generation through nonrelativistic spin splittings, found in uncompensated magnets and d -wave altermagnets (AMs), is desirable for low-power spintronics. Such spin currents, however, are symmetry forbidden in conventional collinear antiferromagnets and higher-order AMs. Using spin-point-group analysis, we demonstrate that finite spin currents can be induced in these materials via magnetoelectric-, piezomagnetic-, and piezomagnetoelectric-like couplings. We utilize electric fields, strain, and their combinations to drive symmetry-lowering phase transitions into uncompensated magnetic or d -wave AM states, thereby enabling finite spin conductivity in a broader class of magnetic materials. We further substantiate this framework using density functional theory and Boltzmann transport calculations on representative magnetic materials— KV 2 Se 2 O , RuF 4 , Cr 2 O 3 , FeS 2 , and MnPSe 3 —spanning these different cases. The charge-to-spin conversion and spin-splitter ratio reaches up to almost 100% via uncompensated magnetism and about 40% via d -wave AM under realistic conditions, highlighting the effectiveness of this approach for efficient spin-current generation.