Superconducting properties and hydrostatic pressure effect on ABi3 (A=Ba,Sr) single crystals

TL;DR

This study reports the growth and characterization of ABi3 (A=Ba,Sr) superconductors, revealing their crystal structures, superconducting transition temperatures, and effects of hydrostatic pressure on their properties.

Contribution

It provides new insights into the crystal structures, pressure dependence, and coupling strength of BaBi3 and SrBi3 superconductors, which were not previously detailed.

Findings

BaBi3 has a Tc of 6.0 K with positive pressure coefficient.

SrBi3 has a Tc of 5.6 K with negative pressure coefficient.

BaBi3 shows weak coupling superconductivity, SrBi3 shows strong coupling.

Abstract

We report on the crystal growth and characterization of ABi3 (A=Ba,Sr) superconductors. Single crystals of both compounds were grown by the self-flux technique. BaBi3 crystallized in a tetragonal structure with space group P4/mmm and SrBi3 in a cubic structure with space group Pm-3m. Superconductivity at Tc = 6.0 K for BaBi3 and Tc = 5.6 K for SrBi3 have been confirmed through dc magnetic susceptibility and electrical transport measurements. The dc magnetic susceptibility under hydrostatic pressure shows a positive pressure coefficient of dTc/dP = 1.22 K/GPa for BaBi3 and a negative pressure coefficient of dTc/dP = -0.48 K/GPa for SrBi3. The normal state electrical resistivity shows that both compounds are highly metallic in nature. The upper critical fields Hc2 evaluated by resistivity under magnetic fields $\rho(T,H)$ are 22 kOe for BaBi3 and 2.9 kOe for SrBi3. A specific heat jump of $\Delta Ce/\gamma Tc = 1.05$ suggests weak coupling superconductivity in BaBi3, whereas $\Delta Ce/\gamma Tc = 2.08$ for SrBi3 is higher than the BCS theory value of 1.43, indicating a strong coupling superconductor.