Evidence for nodal superconductivity in a layered compound Ta$_4$Pd$_3$Te$_{16}$

TL;DR

This study provides evidence of nodal superconductivity in Ta$_4$Pd$_3$Te$_{16}$, a layered compound with quasi-one-dimensional structure, through measurements of the London penetration depth revealing line nodes in the energy gap.

Contribution

It demonstrates the existence of nodal superconductivity in Ta$_4$Pd$_3$Te$_{16}$ using penetration depth measurements and multigap analysis, which is novel for this material.

Findings

Linear temperature dependence of penetration depth at low T

Superfluid density fits a multigap model with nodes

Evidence of line nodes in the superconducting gap

Abstract

We report an investigation of the London penetration depth $\Delta\lambda(T)$ on single crystals of the layered superconductor Ta$_4$Pd$_3$Te$_{16}$, where the crystal structure has quasi-one-dimensional characteristics. A linear temperature dependence of $\Delta\lambda(T)$ is observed for $T\ll T_c$, in contrast to the exponential decay of fully gapped superconductors. This indicates the existence of line nodes in the superconducting energy gap. A detailed analysis shows that the normalized superfluid density $\rho_s(T)$, which is converted from $\Delta\lambda(T)$, can be well described by a multigap scenario, with nodes in one of the superconducting gaps, providing clear evidence for nodal superconductivity in Ta$_4$Pd$_3$Te$_{16}$.