Vortexlike excitations in the heavy-fermion superconductor CeIrIn$_5$

TL;DR

This study investigates vortexlike excitations in the heavy-fermion superconductor CeIrIn$_5$, revealing precursor states to superconductivity with enhanced Nernst signals and suggesting similarities to cuprate superconductors.

Contribution

It provides evidence for vortexlike excitations above $T_c$ in CeIrIn$_5$, highlighting unconventional superconducting precursor states in heavy-fermion systems.

Findings

Enhanced Nernst signal $S_{xy}$ above $T_c$

Positive and amplified $oldsymbol{ abla} oldsymbol{ ext{Peltier}}$ coefficient $oldsymbol{ ext{ extalpha}}_{xy}$

Vortexlike excitations in a precursor state to superconductivity

Abstract

We report a systematic study of temperature- and field-dependent charge ($\boldsymbol{\rho}$) and entropy ($\mathbf{S}$) transport in the heavy-fermion superconductor CeIrIn$_5$. Its large positive thermopower $S_{xx}$ is typical of Ce-based Kondo lattice systems, and strong electronic correlations play an important role in enhancing the Nernst signal $S_{xy}$. By separating the off-diagonal Peltier coefficient $\alpha_{xy}$ from $S_{xy}$, we find that $\alpha_{xy}$ becomes positive and greatly enhanced at temperatures well above the bulk $T_c$. Compared with the non-magnetic analog LaIrIn$_5$, these results suggest vortexlike excitations in a precursor state to unconventional superconductivity in CeIrIn$_5$. This study sheds new light on the similarity of heavy-fermion and cuprate superconductors and on the possibility of states not characterized by the amplitude of an order parameter.