Quantum transport in ferromagnetic permalloy nanostructures

Abstract

We studied phase-coherent phenomena in mesoscopic permalloy (Ni81Fe19) samples by exploring low-temperature transport. Both differential conductance as a function of bias voltage and magnetoconductance of individual wires display conductance fluctuations. Analysis of these fluctuations yields a phase coherence length of 250 nm at 25 mK as well as a 1/sqrt(T) temperature dependence. To suppress conductance fluctuations by ensemble averaging, we investigated low-temperature transport in wire arrays and extended permalloy films. In these samples we have measured conductance corrections which stem from electron-electron interaction; but attempts to detect signatures of weak localization were without success.