Spin injection into silicon detected by broadband ferromagnetic resonance spectroscopy

TL;DR

This study demonstrates spin injection into silicon via broadband ferromagnetic resonance spectroscopy, revealing how silicon doping and layer thickness influence spin pumping efficiency.

Contribution

It provides the first detailed analysis of spin injection into silicon using broadband FMR, highlighting the effects of silicon resistivity and ferromagnetic layer thickness.

Findings

Gilbert damping increases with decreasing silicon resistivity.

Gilbert damping increases with decreasing Py layer thickness.

No damping increase observed with insulating interlayer.

Abstract

We studied the spin injection in a NiFe(Py)/Si system using broadband ferromagnetic resonance spectroscopy. The Gilbert damping parameter of the Py layer on top of the Si channel was determined as a function of the Si doping concentration and Py layer thickness. For fixed Py thickness we observed an increase of the Gilbert damping parameter with decreasing resistivity of the Si channel. For a fixed Si doping concentration we measured an increasing Gilbert damping parameter for decreasing Py layer thickness. No increase of the Gilbert damping parameter was found Py/Si samples with an insulating interlayer. We attribute our observations to an enhanced spin injection into the low-resistivity Si by spin pumping.