Observation of antiferromagnetic order collapse in the pressurized insulator LaMnPO

TL;DR

This study demonstrates the pressure-induced suppression of antiferromagnetic order in LaMnPO, an insulator, revealing a transition to a metallic state and providing insights into potential superconductivity in Mn-based compounds.

Contribution

First observation of pressure-driven collapse of antiferromagnetic order in LaMnPO, highlighting a transition from insulating to metallic state.

Findings

AFM order collapses at ~32 GPa

Transition from insulating to metallic at ~20 GPa

Potential pathway to superconductivity in Mn-based materials

Abstract

The emergence of superconductivity in the iron pnictide and cuprate high temperature superconductors usually accompanies the suppression of an antiferromagnetically (AFM) ordered state in a corresponding parent compound through the use of chemical doping or external pressure1-5. A great deal of effort has been made to find superconductivity in Mn-based compounds6-14, which are thought to bridge the gap between the two families of high temperature superconductors7,15,16, but long-ranged AFM order was not successfully suppressed via chemical doping in these investigations. Here we report the first observation of the pressure-induced elimination of long-ranged AFM order in LaMnPO single crystals that are iso-structural to the LaFeAsO superconductor15,17. By combining in-situ high pressure resistance and ac susceptibility measurements, we found that LaMnPO undergoes a crossover from an AFM insulating to an AFM metallic state at a pressure ~20 GPa and that the long-ranged AFM order collapses at a higher pressure ~32 GPa. Our findings are of importance to explore potential superconductivity in Mn-based compounds and to shed new light on the underlying mechanism of high temperature superconductivity.