Conditions for orbital-selective altermagnetism in Sr2RuO4: Tight-binding model, similarities with cuprates, and implications for superconductivity

Abstract

The vibrational modes in Sr2RuO4 easily induce octahedral rotations without tilting. Being on the verge of a magnetic instability, such propensity of octahedral rotation may also produce magnetic fluctuations. In this work, we analyze the long-range magnetic phase diagram incorporating such octahedral rotations and demonstrate the possibility of an altermagnetic phase in Sr2RuO4. Using ab initio calculations, we first study single-layer Sr2RuO4 with octahedral rotations, obtaining an orbital-selective g-wave altermagnetic phase. We further provide an effective t2g tight-binding model, demonstrating that the g-wave altermagnetism is primarily a product of second- and third-nearest-neighbor interorbital hybridizations between the γz (γ=x,y) orbitals, but only a much longer range intraorbital hybridization in the xy orbitals, establishing a strong orbital selectiveness for the altermagnetism. Notably, by replacing the xy orbital with the x2−y2 orbital, a similar tight-binding model may be used to investigate the hole-doped cuprate superconductors. We then study bulk Sr2RuO4, where we find the altermagnetic phase as the magnetic ground state for a range of finite octahedral rotations. In the bulk, interlayer hopping breaks some of the symmetries of the g-wave altermagnet, resulting in a dxy-wave altermagnet, still with orbital selectiveness. We also include relativistic effects through spin-orbit coupling and obtain that an effective staggered Dzyaloshinskii-Moriya interaction generates weak ferromagnetism. Finally, we discuss the implications of the altermagnetic order on the intrinsic superconductivity of Sr2RuO4. Assuming in-plane intraorbital pairing, the altermagnetism favors spin-singlet dx2−y2-wave or g-wave pairing, or their combinations.

Source-reported materials — not catalogue approval

Similar papers