Ion-exchange synthesis and superconductivity at 8.6 K of Na2Cr3As3 with quasi-one-dimensional crystal structure

TL;DR

This study reports the synthesis of a new quasi-one-dimensional Cr-based superconductor Na2Cr3As3 with a transition temperature of 8.6 K, exhibiting unconventional superconductivity, expanding the family of Cr-based superconductors.

Contribution

The paper introduces a novel ion-exchange synthesis method for Na2Cr3As3 and characterizes its unique quasi-one-dimensional structure and superconducting properties.

Findings

Superconductor Na2Cr3As3 has Tc of 8.6 K.

Crystals exhibit unconventional superconductivity.

Structure features linear (Cr3As3)2- chains separated by Na+ ions.

Abstract

A new Cr-based quasi-one-dimensional superconductor Na2Cr3As3 was synthesized by an ion-exchange method in sodium naphthalenide solution. The crystals are thread-like and the structure was analyzed by X-ray diffraction with a noncentrosymmetric hexagonal space group P-6m2 (No. 187), in which the (Cr3As3)2- linear chains are separated by Na+ ions, and the refined lattice parameters are a = 9.239(2) {\AA} and c = 4.209(6) {\AA}. The measurements for electrical resistivity, magnetic susceptibility, and heat capacity reveal a superconducting transition with unconventional characteristic at the Tc of 8.6 K, which exceeds that of all previously reported Cr-based superconductors.