Anisotropic magnetoresistance and anisotropic tunneling magnetoresistance due to quantum interference in ferromagnetic metal break junctions

TL;DR

This study investigates how quantum interference causes anisotropic magnetoresistance and tunneling magnetoresistance in ferromagnetic break junctions, revealing large angle-dependent resistance changes at low temperatures.

Contribution

It provides experimental evidence linking quantum interference effects to anisotropic magnetoresistance phenomena in ferromagnetic nanostructures.

Findings

Resistance changes up to 25% in tunneling regime

Magnetoresistance pattern sensitive to bias voltage

Quantum interference explains conductance fluctuations

Abstract

We measure the low-temperature resistance of permalloy break junctions as a function of contact size and the magnetic field angle, in applied fields large enough to saturate the magnetization. For both nanometer-scale metallic contacts and tunneling devices we observe large changes in resistance with angle, as large as 25% in the tunneling regime. The pattern of magnetoresistance is sensitive to changes in bias on a scale of a few mV. We interpret the effect as a consequence of conductance fluctuations due to quantum interference.