Nuclear spin pumping by pulling effect

TL;DR

This paper theoretically investigates nuclear spin pumping via hyperfine coupling in NM/FM bilayers, revealing that the pulling effect enhances spin current generated by NMR at low temperatures, surpassing FMR-induced currents.

Contribution

It introduces a theoretical analysis of nuclear spin pumping through hyperfine interactions, highlighting the pulling effect's role in enhancing spin currents in bilayer systems.

Findings

Pulling effect enhances NMR spin current at low temperatures.

NMR-induced spin current can exceed FMR-induced current in certain bilayers.

Theoretical prediction of nuclear spin pumping efficiency in NM/FM systems.

Abstract

The nuclear-to-electron spin angular momentum conversion via hyperfine coupling in a normal metal (NM)/ferromagnet (FM) bilayer system is theoretically investigated by using the nonequilibrium Green's function method. The spin current generated by the nuclear magnetic resonance (NMR) is found to be enhanced by the pulling effect in the FM when the temperature is lower than NMR resonance frequency. In a Co/Pt bilayer system, we show that the spin current by NMR becomes larger than that of the ferromagnetic resonance (FMR).