Large voltage from spin pumping in magnetic tunnel junctions

TL;DR

This paper investigates the large DC voltage generated by spin pumping in magnetic tunnel junctions under RF magnetic fields, revealing significantly higher voltages than in ohmic bilayers, consistent with recent experiments.

Contribution

It provides a theoretical analysis of spin pumping in magnetic tunnel junctions, showing large voltages and damping effects, which were not well understood before.

Findings

DC voltage of microvolts to hundreds of microvolts in tunnel structures

Voltage exceeds that in ohmic ferromagnet-normal metal bilayers

Calculated damping and loss of RF field in the structure

Abstract

We studied the response of a ferromagnet-insulator-normal metal tunnel structure under an external oscillating radio frequency (R.F.) magnetic field. The D. C. voltage across the junction is calculated and is found not to decrease despite the high resistance of the junction; instead, it is of the order of $\mu V$ to $100\mu V$, much larger than the experimentally observed value (100 nano-V) in the "strong coupled" ohmic ferromagnet-normal metal bilayers. This is consistent with recent experimental results in tunnel structures, where the voltage is larger than $\mu V$s. The damping and loss of an external RF field in this structure is calculated.