Magnetic-field dependence of energy levels in ultrasmall metal grains

TL;DR

This paper develops a theoretical model using random matrix theory to analyze how magnetic fields influence energy levels and g tensors in ultrasmall metal grains, revealing the interplay of orbital and spin effects.

Contribution

It introduces a comprehensive model that accounts for both orbital and spin contributions to g tensors, including their behavior across different spin-orbit coupling regimes.

Findings

Orbital and spin contributions to g tensors can be experimentally separated in weak coupling.

Strong spin-orbit coupling causes orbital and spin effects to merge.

Correlations between g factors of neighboring levels are significant at intermediate coupling.

Abstract

We present a theory of mesoscopic fluctuations of g tensors and avoided crossing energies in a small metal grain. The model, based on random matrix theory, contains both the orbital and spin contributions to the g tensor. The two contributions can be experimentally separated for weak spin-orbit coupling while they merge in the strong coupling limit. For intermediate coupling, substantial correlations are found between g factors of neighboring levels.