Detection of spin pumping from YIG by spin-charge conversion in a Au/Ni$_{80}$Fe$_{20}$ spin-valve structure

Nynke Vlietstra, Fasil K. Dejene, Bart J. van Wees

Published 2016-01-21Version 1

Many experiments have shown the detection of spin-currents driven by radio-frequency spin pumping from yttrium iron garnet (YIG), by making use of the inverse spin-Hall effect, which is present in materials with strong spin-orbit coupling, such as Pt. Here we show that it is also possible to directly detect the resonance-driven spin-current using Au/permalloy (Py, Ni$_{80}$Fe$_{20}$) devices, where Py is used as a detector for the spins pumped across the YIG/Au interface. This detection mechanism is equivalent to the spin-current detection in metallic non-local spin-valve devices. By finite element modeling we compare the pumped spin-current from a reference Pt strip with the detected signals from the Au/Py devices. We find that for one series of Au/Py devices the calculated spin pumping signals mostly match the measurements, within 20%, whereas for a second series of devices additional signals are present which are up to a factor 10 higher than the calculated signals from spin pumping. We also identify contributions from thermoelectric effects caused by the resonant (spin-related) and non-resonant heating of the YIG. Thermocouples are used to investigate the presence of these thermal effects and to quantify the magnitude of the Spin-(dependent-)Seebeck effect. Several additional features are observed, which are also discussed.