Electric-Field Tunable Anisotropic <i>g</i> -Factor Induced by Spin Pumping

Spin pumping, a well-established phenomenon where the precessing magnetization of a ferromagnet (FM) injects a pure spin current into an adjacent nonmagnetic layer, is characteristically identified by the enhancement of magnetic damping in the FM. Theoretical work has also suggested that spin pumping can affect the Landé <i>g</i>-factor─another key parameter of ferromagnetic materials besides the magnetic damping. However, experimental evidence of this effect has remained limited. Here, we demonstrate that spin pumping can lead to significant modulation of the <i>g</i>-factor in a Py/AlO_<i>x</i>/STO two-dimensional electron gas (2DEG) system with strong spin-orbit interaction. Specifically, we observe an anisotropic <i>g</i>-factor with 2-fold symmetry below the onset temperature of the 2DEG, and furthermore this anisotropy can be tuned when applying an external electric field. This work uncovers a previously overlooked effect and offers new possibilities for controlling magnetization dynamics in systems with a reduced dimension.