Violation of the Wiedemann-Franz Law in a Large-N Solution of the t-J Model

TL;DR

This paper demonstrates the breakdown of the Wiedemann-Franz law in a large-N solution of the t-J model, aligning with experimental observations in electron-doped cuprates, and highlights the non-Fermi liquid behavior in the normal state.

Contribution

It provides a theoretical large-N analysis of the t-J model showing violation of the Wiedemann-Franz law consistent with experimental data.

Findings

The Wiedemann-Franz law does not hold in the large-N t-J model.

Calculated thermal and electrical conductivities match experimental results.

The phase exhibits non-Fermi liquid properties despite Fermi liquid-like features elsewhere.

Abstract

We show that the Wiedemann-Franz law, which holds for Landau Fermi liquids, breaks down in a large-n treatment of the t-J model. The calculated ratio of the in-plane thermal and electrical conductivities agrees quantitatively with experiments on the normal state of the electron-doped Pr_{2-x}Ce_xCuO_4 (x = 0.15) cuprate superconductor. The violation of the Wiedemann-Franz law in the uniform phase contrasts with other properties of the phase that are Fermi liquid like.