Spin pumping from Lu$_3$Fe$_5$O$_{12}$

Microwave spin pumping from ferromagnetic lutetium iron garnet (Lu$_3$Fe$_5$O$_{12}$) has been theoretically and experimentally investigated. The magnetization vector precession excited by a microwave magnetic field is transformed into a dc voltage due to the inverse spin Hall effect in the lutetium iron garnet/heavy metal heterostructure (Lu$_3$Fe$_5$O$_{12}$/Pt). In the experiments carried out, the external magnetic field has been varied from 0 to 6 kOe, thus making it possible to tune the resonant frequency in wide ranges. The experimental sensitivity of this heterostructure is 8.2 $\mu$V/W. A change in the dc voltage sign with a change in the magnetic field direction confirms the generation of spin current in the Lu$_3$Fe$_5$O$_{12}$/Pt heterostructure. The results obtained make a significant contribution to insight into spin pumping physics and may be useful for the development of new highly sensitive tunable spintronic devices.