Effects of strain on electronic and magnetic properties of altermagnet

We investigate the electronic and magnetic properties of strained altermagnet RuO₂ using the density functional theory plus U (DFT+U) method. RuO₂, as a prototype tetragonal metallic altermagnet, is employed to examine the effects of uniaxial strain on its electronic and magnetic characteristics. The crystal structure is optimized, and the magnetic moments of Ru atoms are calculated as functions of the uniaxial strain. We analyze the electronic band structures and the Fermi surface, revealing that uniaxial strain disrupts the balance between the number of electrons with opposite spin directions. This induces piezomagnetic ferrimagnetism, yielding a nonzero net magnetization that can be tuned by the applied strain. Furthermore, a large uniaxial strain induces a spin-dependent Lifshitz transition of the Fermi surface, potentially leading to significant effects on charge and spin transport properties. These findings highlight the potential of strain engineering in metallic altermagnets for manipulating magnetic and transport properties in spintronic applications.