High pressure study of the normal and superconducting states of the layered pnictide oxide Ba$_{1-x}$Na$_x$Ti$_2$Sb$_2$O with x = 0, 0.10, and 0.15

TL;DR

This study investigates how pressure influences the superconducting and density wave transitions in layered Ba$_{1-x}$Na$_x$Ti$_2$Sb$_2$O, revealing diverse effects on transition temperatures depending on sodium doping levels.

Contribution

It provides the first systematic analysis of pressure effects on both SDW/CDW and superconductivity in this layered pnictide oxide with varying Na content.

Findings

Pressure decreases SDW/CDW transition temperature for x=0 and 0.10.

Superconducting transition temperature increases for x=0 and 0.10 with pressure.

Superconducting transition temperature decreases for x=0.15 with pressure.

Abstract

Here we present a systematic study of the effects of pressure on the superconducting and spin/charge density wave (SDW/CDW) transitions of Ba$_{1-x}$Na$_x$Ti$_2$Sb$_2$O (x = 0, 0.10, and 0.15) by means of resistivity measurements. For x = 0 and 0.10, external pressure results in a decease of the SDW/CDW transition temperature T$_c$; however, no measurable change is observed for the x = 0.15. The pressure effect on the superconducting transition temperature is different for all three samples. For BaTi$_2$Sb$_2$O (x=0), T$_c$ increases significantly from 1.2 K at zero pressure to $\sim$ 2.9 K at 16.1 kbars. The 10 % Na-doped sample shows an initial T$_c$ increase up to 4.2 K with pressure which saturates at higher pressure values. For higher Na concentrations (x=0.15), T$_c$ continuously decreases with increasing pressure.