Tunnel barrier enhanced voltage signal generated by magnetization precession of a single ferromagnetic layer

We report the electrical detection of magnetization dynamics in an Al/AlO(x)/Ni(80)Fe(20)/Cu tunnel junction, where a Ni(80)Fe(20) ferromagnetic layer is brought into precession under ferromagnetic resonance conditions. The dc voltage generated across the junction by the precessing ferromagnet is enhanced about an order of magnitude compared to the voltage signal observed when the contacts in this type of multilayered structure are Ohmic. We discuss the relation of this phenomenon to magnetic spin pumping and speculate on other possible underlying mechanisms responsible for the enhanced electrical signal.