Quantum coherence in a ferromagnetic metal: time-dependent conductance fluctuations

TL;DR

This paper reports the first experimental observation of time-dependent conductance fluctuations in ferromagnetic metals, revealing unique coherence behaviors influenced by magnetic domain dynamics and temperature.

Contribution

It provides the first measurements of quantum conductance fluctuations in ferromagnetic metals and explores the effects of magnetic domain motion on electron coherence.

Findings

Suppression of cooperon contribution in ferromagnetic conductance fluctuations

Domain wall motion enhances conductance fluctuations

Temperature dependence suggests an unusual dephasing mechanism

Abstract

Quantum coherence of electrons in ferromagnetic metals is difficult to assess experimentally. We report the first measurements of time-dependent universal conductance fluctuations in ferromagnetic metal (Ni$_{0.8}$Fe$_{0.2}$) nanostructures as a function of temperature and magnetic field strength and orientation. We find that the cooperon contribution to this quantum correction is suppressed, and that domain wall motion can be a source of coherence-enhanced conductance fluctuations. The fluctuations are more strongly temperature dependent than those in normal metals, hinting that an unusual dephasing mechanism may be at work.