Enhanced Gilbert Damping via Cubic Spin-Orbit Coupling at 2DHG/Ferromagnetic Insulator Interface

We investigate the enhancement of Gilbert damping at 2DHG/ferromagnetic insulator (FI) interfaces, where spin pumping from the FI layer injects spins into the 2DHG, and cubic Rashba spin-orbit coupling (RSOC) significantly boosts spin relaxation and spin-pumping efficiency compared to 2DEG systems. The dominant contribution to spin damping arises from interband transitions which does exhibits conductivity-like behavior as the temperature, $T \to 0$. Our results reveal that damping remains stronger than in 2DEG due to the persistent influence of cubic RSOC. The interplay between RSOC and magnon absorption broadens the spectral response, with the damping peak shifting more notably at higher temperatures. Stronger RSOC expands the magnon interaction phase space, thus widening the damping spectrum. A key observation emerges with the Fermi level ($E_f$): a finite $E_f$ sustains spin imbalance and enhances damping, whereas $E_f = 0$ suppresses it, unlike in 2DEG. The electric field tunability of RSOC enables real-time control over spin relaxation and angular momentum transfer, offering a pathway toward voltage-controlled spintronic devices. These findings highlight the superior potential of 2DHG for tailoring spin dynamics via electric and thermal effects.