Thermodynamics of ultra-small metallic grains in the auxiliary-field Monte Carlo approach

TL;DR

This paper employs an auxiliary-field Monte Carlo method to analyze thermodynamic properties of ultra-small metallic grains, bridging the gap between bulk and fluctuation-dominated regimes at finite temperatures.

Contribution

It introduces a renormalization technique that reduces computational effort, enabling detailed study of pairing correlations in ultra-small metallic grains.

Findings

Successful calculation of spin susceptibility and heat capacity

Demonstration of crossover from bulk to fluctuation-dominated regime

Efficient computational approach at low temperatures

Abstract

We use an auxiliary-field Monte Carlo (AFMC) method to calculate thermodynamic properties (spin susceptibility and heat capacity) of ultra-small metallic grains in the presence of pairing correlations. This method allows us to study the crossover from bulk systems, where mean-field BCS theory is valid, to the fluctuation-dominated regime of ultra-small particles at finite temperature. The computational effort at low temperatures is significantly reduced by exploiting a simple renormalization method.