Conductance of Mesoscopic Systems with Magnetic Impurities

TL;DR

This paper analyzes how magnetic impurities and magnetic fields influence conductance in disordered metals, revealing mechanisms that enhance localization effects and enable extraction of impurity properties from conductance oscillations.

Contribution

It provides analytical expressions for conductance corrections considering magnetic impurity polarization and magnetic fields, applicable to experimental data analysis.

Findings

Magnetic impurity polarization reduces electron phase relaxation rate.

Magnetic field suppresses impurity thermal fluctuations, recovering conductance fluctuations.

Analytical formulas for conductance oscillations enable impurity property extraction.

Abstract

We investigate the combined effects of magnetic impurities and applied magnetic field on the interference contribution to the conductance of disordered metals. We show that in a metal with weak spin-orbit interaction, the polarization of impurity spins reduces the rate of electron phase relaxation, thus enhancing the weak localization correction to conductivity. Magnetic field also suppresses thermal fluctuations of magnetic impurities, leading to a recovery of the conductance fluctuations. This recovery occurs regardless the strength of the spin-orbit interaction. We calculate the magnitudes of the weak localization correction and of the mesoscopic conductance fluctuations at an arbitrary level of the spin polarization induced by a magnetic field. Our analytical results for the ``$h/e$'' Aharonov-Bohm conductance oscillations in metal rings can be used to extract spin and gyromagnetic factor of magnetic impurities from existing experimental data.