Synthesizing and characterization of hole doped nickel based layer superconductor (La$_{1-x}$Sr$_{x}$)ONiAs

TL;DR

This study synthesizes and characterizes a hole-doped Ni-based superconductor, showing increased $T_c$ with Sr doping and revealing the evolution of charge carriers from electron-like to hole-like.

Contribution

It demonstrates the successful hole doping of LaONiAs, increasing $T_c$, and provides insights into charge carrier evolution and normal state properties.

Findings

$T_c$ increases from 2.75 K to 3.7 K with Sr doping

Normal state resistivity shows metallic behavior without anomalies

Hall effect indicates a transition from electron-like to hole-like conduction

Abstract

We report the synthesizing and characterization of the hole doped Ni-based superconductor ($La_{1-x}Sr_{x})ONiAs$. By substituting La with Sr, the superconducting transition temperature $T_c$ is increased from 2.75 K of the parent phase $LaONiAs$ to 3.7 K at the doping levels x= 0.1 - 0.2. The curve $T_c$ versus hole concentration shows a symmetric behavior as the electron doped samples $La(O_{1-x}F_{x})NiAs$. The normal state resistivity in Ni-based samples shows a good metallic behavior and reveals the absence of an anomaly which appears in the Fe-based system at about 150 K, suggesting that this anomaly is not a common feature for all systems. Hall effect measurements indicate that the electron conduction in the parent phase $LaONiAs$ is dominated by electron-like charge carriers, while with more Sr doping, a hole-like band will emerge and finally prevail over the conduction, and accordingly the superconducting transition temperature $T_c$ increases.