Field- and temperature-modulated spin diode effect in a GMR nanowire with dipolar coupling

Piotr Ogrodnik,Jakub Chęciński,Jean-Philippe Ansermet,Francesco Antonio Vetrò,Józef Barnaś,Marek Frankowski,Tomasz Stobiecki

doi:10.1088/1361-6463/aaf093

Abstract

The magnetization dynamics of single Co/Cu/Co spin valves, embedded in electrodeposited nanowires of 30 nm avarage diameter, was observed using the spin-diode effect. The electrically-detected magnetic resonances were compared when using modulation of either the magnetic field or a laser irradiation. The effect of temperature modulation was accounted for by introducing the temperature dependence of the saturation magnetization and anisotropy, as well as thermal spin-transfer torque (TSTT). The predictions of the model are compared with experimental data. Two forms of modulation give rise to qualitative differences in the spectra that are accounted for by the model only if both temperature-modulated magnetization and TSTT are introduced in the model. On the contrary, the temperature modulation of the magnetic anisotropy has a smaller contribution.

Highlights

The spin diode effect (SDE) is a well established method of electrical detection of magnetic dynamics in ferromagnetic layers.[1,2,3,4,5,6,7,8] The effect occurs when an alternating current (AC) passes through a magnetic structure and excites oscillations of the magnetization vector
The nanowires under consideration consist of two cobalt ferromagnetic layers separated by a non-magnetic Cu spacer
Because of the electrochemical deposition method used to fabricate the nanowires, the thin layer in an individual nanowire may have slightly different magnetic properties than the corresponding thick layer. This is due to the presence of copper atoms that are codeposited in the magnetic layers

Summary

Introduction

The spin diode effect (SDE) is a well established method of electrical detection of magnetic dynamics in ferromagnetic layers.[1,2,3,4,5,6,7,8] The effect occurs when an alternating current (AC) passes through a magnetic structure and excites oscillations of the magnetization vector. In some of the experimentally investigated structures there are two or more layers which are magnetically free and, in addition, are dynamically coupled by the RKKY-like exchange interaction and/or by dipolar interactions.[9,10,11,12,13] they are dynamically coupled by spin transfer torque (STT) effects.[14] most of these devices with multiple free magnetic layers, still include at least one, usually thick, pinned magnetic polarizer.[15,16]

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