A Model for the Schottky Anomaly in Metallic $Nd_{2-y}Ce_{y}CuO_{4}$

TL;DR

This paper introduces a simple Hartree-Fock based model to explain the Schottky anomaly and magnetic properties in doped Nd2-yCeyCuO4, aligning well with experimental observations.

Contribution

It presents a novel impurity Anderson-like model within a Hartree-Fock framework to describe magnetic and thermal behaviors in doped cuprates.

Findings

Schottky anomaly peak shifts with Ce doping

Low-temperature specific heat is linear in overdoped samples

Magnetic susceptibility transitions from constant to Curie-like with temperature

Abstract

We present a simple model for the doped compound $Nd_{2-y}Ce_{y}CuO_{4}$, in order to explain some recent experimental results on the latter. Within a Hartree-Fock context, we start from an impurity Anderson-like model and consider the magnetic splitting of the $Nd$-$4f$ ground state Kramers doublet due to exchange interactions with the ordered $Cu$ moments. Our results are in very good agreement with the experimental data, yielding a Schottky anomaly peak for the specific heat that reduces its amplitude, broadens and shifts to lower temperatures, upon $Ce$ doping. For overdoped compounds at low temperatures, the specific heat behaves linearly and the magnetic susceptibility is constant. A smooth transition from this Fermi liquid like behavior ocurrs as temperature is increased and at high temperatures the susceptibility exhibits a Curie-like behavior. Finally, we discuss some improvements our model is amenable to incorporate.