Pressure-induced superconductivity up to 9 K in the quasi-one-dimensional KMn6Bi5

TL;DR

This study reports the discovery of pressure-induced superconductivity up to 9 K in the quasi-one-dimensional KMn6Bi5, marking it as the first Mn-based superconductor with potential unconventional pairing mechanisms.

Contribution

It is the first to demonstrate pressure-induced superconductivity in a Mn-based compound, expanding the understanding of magnetic pair-breaking effects and structural flexibility in such materials.

Findings

Superconductivity emerges at 13 GPa with T_c up to 9.3 K.

Superconductivity is closely linked to suppression of antiferromagnetic order.

Large upper critical field suggests unconventional pairing mechanism.

Abstract

The Mn-based superconductor is rare owing to the strong magnetic pair-breaking effect. Here we report on the discovery of pressure-induced superconductivity in KMn6Bi5, which becomes the first ternary Mn-based superconductor. At ambient pressure, the quasi-one-dimensional KMn6Bi5 is an antiferromagnetic metal with TN = 75 K. By measuring resistivity and ac magnetic susceptibility under hydrostatic pressures up to 14.2 GPa in a cubic anvil cell apparatus, we find that its antiferromagnetic transition can be suppressed completely at a critical pressure of Pc = 13 GPa, around which bulk superconductivity emerges and displays a superconducting dome with the maximal Tconset = 9.3 K achieved at about 14.2 GPa. The close proximity of superconductivity to a magnetic instability in the temperature-pressure phase diagram of KMn6Bi5 and an unusually large {\mu}0Hc2(0) = 18.9 T exceeding the Pauli limit suggests an unconventional magnetism-mediated paring mechanism. In contrast to the binary MnP, the flexibility of the crystal structure and chemical compositions in the ternary AMn6Bi5 (A = alkali metal) can open a new avenue for finding more Mn-based superconductors.