Current Induced Excitations in Cu/Co/Cu Single Ferromagnetic Layer Nanopillars

TL;DR

This study experimentally investigates current-induced magnetic excitations in Cu/Co/Cu nanopillars, revealing asymmetry-dependent spin wave excitations consistent with spin-transfer torque predictions.

Contribution

It provides the first experimental confirmation of spin-transfer torque induced excitations in single-layer ferromagnetic nanopillars with structural asymmetry.

Findings

Asymmetric junctions show excitations at high current densities for one polarity.

Symmetric junctions do not exhibit such excitations.

Results confirm theoretical predictions of spin-transfer torque effects in single-layer structures.

Abstract

Current-induced magnetic excitations in Cu/Co/Cu single layer nanopillars (~50 nm in diameter) have been studied experimentally as a function of Co layer thickness at low temperatures for large applied fields perpendicular to the layers. For asymmetric junctions current induced excitations are observed at high current densities for only one polarity of the current and are absent at the same current densities in symmetric junctions. These observations confirm recent predictions of spin-transfer torque induced spin wave excitations in single layer junctions with a strong asymmetry in the spin accumulation in the leads.