Coexistence of antiferromagnetism and superconductivity in the Anderson lattice

TL;DR

This paper investigates the competition and coexistence of antiferromagnetism and d-wave superconductivity in an Anderson lattice, revealing a pressure-induced quantum phase transition with distinct optical conductivity features.

Contribution

It introduces a mean field theoretical framework for the Anderson lattice that captures the interplay between antiferromagnetism and superconductivity, highlighting a pressure-driven quantum phase transition.

Findings

Quantum phase transition with magnetic order expulsion by superconductivity under pressure.

Development of a double peak structure in optical conductivity below magnetic transition temperature.

Calculation of quasiparticle bands and density of states in ordered phases.

Abstract

We study the interplay between antiferromagnetism and superconductivity in a generalized infinite-$U$ Anderson lattice, where both superconductivity and antiferromagnetic order are introduced phenomenologically in mean field theory. In a certain regime, a quantum phase transition is found which is characterized by an abrupt expulsion of magnetic order by d-wave superconductivity, as externally applied pressure increases. This transition takes place when the d-wave superconducting critical temperature, $T_c$, intercepts the magnetic critical temperature, $T_m$, under increasing pressure. Calculations of the quasiparticle bands and density of states in the ordered phases are presented. We calculate the optical conductivity $\sigma(\omega)$ in the clean limit. It is shown that when the temperature drops below $T_m$ a double peak structure develops in $\sigma(\omega)$.