Thermodynamic properties of the periodic Anderson model:X-boson treatment

TL;DR

This paper investigates the thermodynamic properties of the periodic Anderson model in the infinite-U limit using the X-boson method, revealing multiple peaks in specific heat and effective mass behavior consistent with experimental heavy fermion systems.

Contribution

It applies the X-boson treatment to analyze the periodic Anderson model in two regimes, providing new insights into specific heat and entropy behaviors matching experimental observations.

Findings

Multiple peak structure in specific heat.

Effective mass increases at low temperatures.

Entropy behavior varies with ground state type.

Abstract

We study the specific dependence of the periodic Anderson Model (PAM) in the limit of $U=\infty$ employing the X-boson treatment in two fifferent regimes of the PAM: the heavy fermion Kondo (HF-K) and the heavy fermion local magnetic regime (HF-LMM). We obtain a multiple peak structure for the specific heat in agreement with experimental results as well as the increase of the electronic effective mass at low temperatures associated with the HF-K regime. The entropy per site at low T tends to zero in the HF-K regime, corresponding to a singlet ground state, and it tends to $k_{B}ln(2)$ in the HF-LMM, corresponding to a doublet ground state at each site. The linear coefficient $\gamma(T)=C_{v}/T$ of the specific heat qualitatively agrees with the experimental results obtained for differents materials in the two regimes considered here.