Tuning of altermagnetism by strain

For all collinear altermagnets, we sort out piezomagnetic free-energy invariants allowed in the nonrelativistic limit and relativistic piezomagnetic invariants bilinear in the Neel vector L and magnetization M, which include strain-induced Dzyaloshinskii-Moriya interaction. In the nonrelativistic limit, I present two distinct mechanisms of piezomagnetism: 1) the band-filling mechanism, which exists in metals and 2) the temperature-dependent exchange-driven mechanism typical for insulators. The two mechanisms are illustrated by analytical results for Lieb lattice model and by numerical calculations for CrSb. I show how the triplet Cooper pairs supported by inversion symmetry become non-unitatry under the action of pizomagnetically active strain.