Anisotropic spin fluctuations in Sr2RuO4: Role of spin-orbit coupling and induced strain
Cobo, S, Ahn, F, Eremin, I, Akbari, A.
Phys. Rev. B 94 , 224507 (2016).
We analyze the spin anisotropy of the magnetic susceptibility of Sr2RuO4 in the presence of spin-orbit coupling and anisotropic strain using quasi-two-dimensional tight-binding parametrization fitted to the angle-resolved photoemission spectroscopy results. Similar to the previous observations we find the in-plane polarization of the low-q magnetic fluctuations and the out-of-plane polarization of the incommensurate magnetic fluctuation at the nesting wave-vector Q1=(2/3π,2/3π) but also nearly isotropic fluctuations near Q2=(π/6,π/6). Furthermore, one finds that, apart from the high-symmetry direction of the tetragonal Brillouin zone, the magnetic anisotropy is maximal, i.e., χxx≠χyy≠χzz reflected in the x polarization of the intraband nesting wave-vector Q3=(π/2,π). This is a consequence of the orbital anisotropy of the t2g orbitals in momentum space. We also study how the magnetic anisotropy evolves in the presence of the strain and find strong Ising-like ferromagnetic fluctuations near the Lifshitz transition for the xy band.