Anomalous Pressure Dependence of the Superconducting Transition Temperature in TlNi$_2$Se$_{2-x}$S$_x$

TL;DR

This study investigates how pressure affects the superconducting transition temperature in TlNi$_2$Se$_{2-x}$S$_x$, revealing unexpected collapse and dome-shaped behavior, indicating complex interactions between sulfur substitution and pressure.

Contribution

It provides the first detailed pressure-temperature phase diagram for TlNi$_2$Se$_{2-x}$S$_x$, uncovering novel superconducting phenomena and the nontrivial effects of sulfur substitution.

Findings

Superconductivity collapses abruptly at moderate pressure.

$T_c$ exhibits a dome-shaped dependence on pressure for TlNi$_2$SeS.

Sulfur substitution interacts complexly with applied pressure.

Abstract

We report the pressure dependence of the superconducting transition temperature, $T_c$, in TlNi$_2$Se$_{2-x}$S$_x$ detected via the AC susceptibility method. The pressure-temperature phase diagram constructed for TlNi$_{2}$Se$_{2}$, TlNi$_{2}$S$_{2}$ and TlNi$_{2}$SeS exhibits two unexpected features: (a) a sudden collapse of the superconducting state at moderate pressure for all three compositions and (b) a dome-shaped pressure dependence of $T_c$ for TlNi$_{2}$SeS. These results point to the nontrivial role of S substitution and its subtle interplay with applied pressure, as well as novel superconducting properties of the TlNi$_2$Se$_{2-x}$S$_x$ system.