Flipping of antiferromagnetic to superconducting states in pressurized quasi-one-dimensional manganese-based compounds

TL;DR

This study demonstrates pressure-induced transition from antiferromagnetic to superconducting states in quasi-one-dimensional manganese-based compounds, revealing orbital contributions as a key factor in this flipping phenomenon.

Contribution

It reports the first observation of a pressure-driven AFM to SC transition in AMn6Bi5 compounds without structural changes, highlighting orbital effects in the transition.

Findings

AFM state disappears and SC emerges at a critical pressure

Transition occurs at similar pressures despite volume differences

Orbital electron changes may drive the AFM-SC flipping

Abstract

One of the universal features of unconventional superconductors is that the superconducting (SC) state is developed in the proximity of an antiferromagnetic (AFM) state. Understanding the interplay between these two states is one of the key issues to uncover the underlying physics of unconventional SC mechanism. Here, we report a pressure-induced flipping of the AFM state to SC state in the quasi-one-dimensional AMn6Bi5 (A = K, Rb, and Cs) compounds. We find that at a critical pressure the AFM state suddenly disappears at a finite temperature and a SC state simultaneously emerges at a lower temperature without detectable structural changes. Intriguingly, all members of the family present the AFM-SC transition at almost the same critical pressures (Pc), though their ambient-pressure unit-cell volumes vary substantially. Our theoretical calculations indicate that the increasing weight of dxz orbital electrons near Fermi energy under the pressure may be the origin of the flipping. These results reveal a diversity of competing nature between the AFM and SC states among the 3d-transition-metal compounds.