Magnetic properties of Co doped Nb clusters

TL;DR

This study investigates the magnetic behavior of Co-doped Nb clusters through combined experimental and theoretical methods, revealing that non-magnetic clusters result from local moment quenching rather than the Kondo effect, with magnetism influenced by electronic hybridization.

Contribution

The paper provides a detailed analysis of the origin of magnetic and non-magnetic states in Co-doped Nb clusters using vibrational spectra, density functional theory, and the Anderson impurity model, clarifying the physical mechanisms involved.

Findings

Non-magnetic clusters are due to quenching of the Co local moment.

Magnetic behavior correlates with low effective hybridization around the chemical potential.

Experimental vibrational spectra match DFT calculations, confirming ground state geometries.

Abstract

From magnetic deflection experiments on isolated Co doped Nb clusters we made the interesting observation of some clusters being magnetic, while others appear to be non-magnetic. There are in principle two explanations for this behavior. Either the local moment at the Co site is completely quenched or it is screened by the delocalized electrons of the cluster, i.e. the Kondo effect. In order to reveal the physical origin, we conducted a combined theoretical and experimental investigation. First, we established the ground state geometry of the clusters by comparing the experimental vibrational spectra with those obtained from a density functional theory study. Then, we performed an analyses based on the Anderson impurity model. It appears that the non-magnetic clusters are due to a complete quenching of the local Co moment and not due to the Kondo effect. In addition, the magnetic behavior of the clusters can be understood from an inspection of their electronic structure. Here magnetism is favored when the effective hybridization around the chemical potential is small, while the absence of magnetism is signalled by a large effective hybridization around the chemical potential.