Interplay of Superconductivity and Fermi-Liquid Transport in Rh-Doped CaFe2As2 with Lattice-Collapse Transition

TL;DR

This study investigates how Rh doping in CaFe2As2 influences its structural phases, superconductivity, and Fermi-liquid behavior, revealing the critical role of magnetic fluctuations in superconductivity emergence.

Contribution

It uncovers the relationship between lattice structure, Fermi-liquid transport, and superconductivity in Rh-doped CaFe2As2, highlighting the importance of magnetic fluctuations.

Findings

Superconductivity appears in the uncollapsed-tetragonal phase at specific Rh doping levels.

Fermi-liquid transport breaks down above Tc in the superconducting phase.

Restoration of Fermi-liquid behavior coincides with the loss of superconductivity in the collapsed-tetragonal phase.

Abstract

Ca(Fe$_{1-x}$Rh$_x$)$_2$As$_2$ undergoes successive phase transitions with increasing Rh doping in the $T$ $=$ 0 limit. The antiferromagnetic-metal phase with orthorhombic structure at 0.00 $\le$ $x$ $\le$ 0.020 is driven to a superconducting phase with uncollapsed-tetragonal (ucT) structure at 0.020 $\le$ $x$ $\le$ 0.024; a non-superconducting collapsed-tetragonal (cT) phase takes over at $x$ $\geq$ 0.024. The breakdown of Fermi-liquid transport is observed in the ucT phase above $T_{\rm c}$. In the adjacent cT phase, Fermi-liquid transport is restored along with a disappearance of superconductivity. This interplay of superconductivity and Fermi-liquid transport suggests the essential role of magnetic fluctuations in the emergence of superconductivity in doped CaFe$_2$As$_2$.