Inverse Spin Hall Effect Dominated Spin-Charge Conversion in (101) and (110)-Oriented RuO2 Films

Utilizing spin pumping, we present a comparative study of the spin-charge conversion in RuO₂ (101) and RuO₂ (110) films. RuO₂ (101) shows a robust in-plane crystal-axis dependence, whereas RuO₂ (110) exhibits an isotropic but stronger one. Symmetry-based analysis and first-principles calculations reveal that the spin-charge conversion in RuO₂ (110) originates from the inverse spin Hall effect (ISHE) due to nodal lines splitting. In RuO₂ (101), the ISHE also dominates although the inverse spin splitting effect (ISSE) may coexist. These findings, in sharp contrast to previously attributed ISSE, are further corroborated by the reciprocal relation between the spin pumping and the spin-torque ferromagnetic resonance measurements.