Ba1-xNaxTi2Sb2O (0.0 <= x <= 0.33): A Layered Titanium-based Pnictide Oxide Superconductor

TL;DR

This paper reports the discovery of a new layered titanium-based pnictide oxide superconductor, Ba1-xNaxTi2Sb2O, which exhibits superconductivity upon doping and shows similarities to cuprates and iron pnictides.

Contribution

It introduces a novel Ti-based pnictide oxide superconductor with detailed structural and superconducting properties, expanding the family of layered superconductors.

Findings

Superconductivity emerges after doping with Na.

Critical temperature reaches 5.5 K.

Doping suppresses CDW/SDW transition.

Abstract

A new layered Ti-based pnictide oxide superconductor, Ba1-xNaxTi2Sb2O (0.0 <= x <= 0.33), is reported. X-ray studies reveal it crystallizes in the tetragonal CeCr2Si2C structure. The undoped parent compound, BaTi2Sb2O (P4/mmm; a=4.1196(1){\AA}; c=8.0951(2){\AA}), exhibits a CDW/SDW transition at 54K. Upon chemical doping with Na, the CDW/SDW transition is systematically suppressed and super-conductivity arises with the critical temperatures, Tc, increasing to 5.5 K. Bulk superconductivity is confirmed by resistivity, magnetic and heat capacity measurements. Like the high-Tc cuprates and the iron pnictides, superconductivity in BaTi2Sb2O arises from an ordered state. Similarities and differences to the cuprate and iron pnictide supercon-ductors are discussed.