A New Noncentrosymmetric Superconducting Phase in the Li-Rh-B System

TL;DR

This paper reports the discovery of a new noncentrosymmetric superconducting phase in the Li-Rh-B system with a maximum Tc of about 3 K, highlighting its structural features, stability, and magnetic properties.

Contribution

It introduces a novel noncentrosymmetric cubic phase in the Li-Rh-B system and characterizes its superconducting properties and stability range.

Findings

Superconductivity observed at 2-3 K in a new phase.

The phase has a large noncentrosymmetric cubic unit cell.

Superconductivity persists over a wide compositional range.

Abstract

Superconductivity, at 2-3 K, was observed in a novel phase of the ternary Li-Rh-B system. The structural phase exhibits a large noncentrosymmetric cubic unit cell with the a-parameter being within 1.208 \leq a \leq 1.215 nm. This phase is stable over a wider compositional range of LixRhBy (0.6 < x < 2, 1 < y < 2). The superconductivity, as well as the unit cell volume, is sensitive to the Li/B content but it is manifested with Tc \geq 1.8 K over a wider compositional range: the highest Tc \approx 3 K occurs for x : y \approx 0.9:1.5 with a \approx 1.209 nm. The superconducting shielding fraction of most samples is almost 80% of that of Sn. The lower critical field, Hc1(0), is ~65 Oe while the upper one, Hc2(0) is determined from extrapolation to be higher than 14 kOe. We discuss the influence of pressure on Tc and also the influence of the lack of inversion symmetry on the superconducting properties.