Electronic structure of itinerant antiferromagnet RuO­_2­ under strain

Rutile RuO­_2­­ has long been considered as an ordinary metallic paramagnet in its ground state. It is, however, recently proved by neutron diffraction experiment to be an itinerant antiferromagnet with Néel temperature above 300 K. More interestingly, RuO­­_2­ is shown to have momentum-dependent spin polarization due to its unique symmetry in real space, leading to non-spin degenerate Fermi surface. The spin splitting effect in AFM RuO­₂ is regarded as an anomalous phenomenon since the AFM state is collinear and non-frustrated with a centrosymmetric center and without spin-orbit coupling. Given this unique magnetic structure, RuO­­­_{2 ­}proved to host interesting properties such as giant tunneling magnetoresistance, anomalous Hall effect, time-reversal-odd spin Hall conductivity amongst others. In addition, epitaxial and uniaxial strain were applied to thin film RuO­_2­, giving rise to fascinating observations ranging from superconductivity below 2 K to enhanced oxygen evolution reaction performance. In this study, using the state-of-the-art first principles calculations we explore the electronic structure of RuO­₂ under various strain conditions. We address the interplay between spin, orbital, and lattice degrees of freedom as well as the strained-induced effects on its band structure. Initial results show that applying strain modifies the RuO­_2­ electronic structure, i.e., altering the Fermi surface topology, establishing the controlled strain-manipulation of the electronic transport properties of RuO₂.