Magnon Spin Current Modulation through Magnetic Ion Doping in a Compensated Iron Garnet

Abstract We report on the impact of manganese doping at the iron sites in Gadolinium Iron Garnet (GdIG, Gd$_{3}$Fe$_{5}$O$_{12}$), employing temperature-dependent spin Seebeck effect and ferromagnetic resonance measurements. Our findings reveal a clear shift in the magnetic compensation temperature $( T_{comp})$ in Mn-doped GdIG, with minimal changes observed in the magnetic and damping properties. Notably, the spin Seebeck signal strength was enhanced significantly with the Mn doping. This enhancement is plausibly associated with an increased spin mixing conductance and modifications in the magnon spectra, highlighting the tunability of GdIG’s spin Seebeck response and its potential for room-temperature spintronic applications.