Kondo Effect and Spin Glass Behavior of Dilute Iron Clusters in Silver Studied by M\"{o}ssbauer Spectroscopy and Resistivity

TL;DR

This study investigates how dilute iron clusters in silver exhibit Kondo effect and spin glass behavior, using Mössbauer spectroscopy and resistivity measurements to analyze magnetic interactions and cluster formation.

Contribution

It provides new insights into the formation of nanometer-sized iron clusters and their magnetic behavior, highlighting the interplay of Kondo effect and RKKY interactions in dilute metal alloys.

Findings

Identification of ferromagnetic mono-domain clusters

Observation of magnetic freezing at low temperatures

Non-monotonic resistivity variation due to competing effects

Abstract

Thin films of silver containing 0.3 - 1.5 at % Fe have been prepared by vapor co-deposition. Depending on substrate temperature and iron concentration we could systematically follow the formation of nanometer size clusters of iron from initially dilute iron monomers. samples were characterized via X-ray diffraction, resistivity and M\"{o}ssbauer spectroscopic measurements. The magnetic behavior derived from M\"{o}ssbauer data can be best described with an ensemble of ferromagnetic mono-domain particles. The magnetic freezing observed at low temperatures, is controlled via the inter-particle interactions mediated via conduction electron polarization, i.e. RKKY interaction. The interaction of the cluster magnetic moments with the conduction electron sea is best quantified by the electrical resistivity data. For all studied concentrations we find a non-monotonic variation with temperature which can be understood by competing shielding of the cluster moments by conduction electron spin scattering due to Kondo effect and the magnetic coupling.