Studies of Current-Driven Excitations in Co/Cu/Co Trilayer Nanopillars

TL;DR

This study investigates the current-driven magnetic excitations in Co/Cu/Co nanopillars by measuring dynamic resistance, revealing symmetric and asymmetric behaviors, telegraph noise effects, and the influence of magnetic field and current variations.

Contribution

It provides new insights into the magnetization stability diagram and the effects of current and magnetic field on nanopillar resistance behaviors, including telegraph noise analysis.

Findings

Resistance behavior is symmetric in magnetic field at various currents.

Telegraph noise influences the differential resistance peaks.

Asymmetric magnetic field responses and negative switching peaks are observed.

Abstract

We measure the dynamic resistance of a Co/Cu/Co trilayer nanopillar at varied magnetic field $H$ and current $I$. The resistance displays the usual behavior, almost symmetric in $H$, both when magnetization switching is hysteretic at small $I,H$, and reversible at larger $I,H$. We show differences in the $I,H$ magnetization stability diagram measured by holding $I$ fixed and varying $H$ and vice versa. We also show how the peak in $dV/dI$ associated with telegraph noise in the reversible switching regime, is calculated from the telegraph noise variations with $I$. Lastly, we show data for a similar sample that displays behavior asymmetric in $H$, and a negative reversible switching peak instead of a usual positive one.