Micro(point)contact spectroscopy of dilute magnetic (Kondo) alloys CuMn and CuFe

TL;DR

This study uses microcontact spectroscopy to analyze dilute magnetic alloys CuMn and CuFe, revealing zero-bias anomalies and enabling the determination of impurity parameters and contact geometry with good agreement to theoretical models.

Contribution

It introduces a quantitative method to extract magnetic impurity characteristics and contact parameters from microcontact spectra of dilute magnetic alloys.

Findings

Observation of zero-bias anomalies at ~1 mV in spectra.

Determination of Lande g-factor for Mn impurities.

Quantitative agreement with theoretical models.

Abstract

The method of microcontact spectroscopy is used to study alloys with magnetic impurities CuMn and CuFe in the range of concentrations 0.01-1 at.%. Minima or maxima (so-called zero-bias anomalies) were observed in the microcontact spectra of these alloys at voltages ~ 1 mV. The Lande g-factor for the Mn impurity in a Cu matrix was determined from the splitting of the minimum of the zero-bias anomaly in a magnetic field. The quantitative calculations carried out agree well with theory and permit determining both the important geometric contact parameter <K> i.e., the averaged geometric form factor, and the characteristics of the alloy itself, for example, J/E_F, i.e., the ratio of the magnitude of the exchange interaction energy between an electron and the magnetic impurity to the Fermi energy, from the microcontact spectra.