Emergence of superconductivity on the border of antiferromagnetic order in RbMn6Bi5 under high pressure: A new family of Mn-based superconductors

TL;DR

This study reports the discovery of pressure-induced superconductivity in RbMn6Bi5, a Mn-based compound near antiferromagnetic order, revealing a new family of unconventional superconductors with high critical temperatures.

Contribution

It introduces RbMn6Bi5 as a new Mn-based superconductor family and details its pressure-induced superconductivity and phase diagram.

Findings

Superconductivity emerges at 13 GPa with Tc up to 9.5 K.

Large upper critical field exceeds Pauli limit, indicating unconventional pairing.

Phase diagram resembles magnetism-mediated superconducting systems.

Abstract

The advances in the field of unconventional superconductivity are largely driven by the discovery of novel superconducting systems. Here we report on the discovery of superconductivity on the border of antiferromagnetic order in a quasi-one-dimensional RbMn6Bi5 via measurements of resistivity and magnetic susceptibility under high pressures. With increasing pressure, its antiferromagnetic transition with TN = 83 K at ambient pressure is first enhanced moderately and then suppressed completely at a critical pressure of Pc = 13 GPa, around which bulk superconductivity emerges and exhibits a dome-like Tc(P) with a maximal Tc_onset = 9.5 K at about 15 GPa. Its temperature-pressure phase diagram resembles those of many magnetism-mediated superconducting systems. In addition, the superconducting state around Pc is characterized by a large upper critical field {\mu}0Hc2(0) exceeding the Pauli limit, elaborating a possible unconventional paring mechanism. The present study, together with our recent work on KMn6Bi5 (Tcmax = 9.3 K), makes AMn6Bi5 (A= Alkali metal) a new family of Mn-based superconductors with relatively high Tc.