Structural and Magnetic Phase Transitions in NdCoAsO under High Pressures

TL;DR

This study explores how high pressure influences the structural and magnetic phase transitions in NdCoAsO, revealing increased magnetic transition temperatures and a structural phase change at 23 GPa, without inducing superconductivity.

Contribution

It provides the first detailed high-pressure phase diagram of NdCoAsO, highlighting pressure-induced magnetic and structural transitions without superconductivity.

Findings

Curie and Neel temperatures increase with pressure

Structural phase transition at 23 GPa from tetragonal to new phase

NdCoAsO remains antiferromagnetic and non-superconducting up to 53 GPa

Abstract

We have investigated structural and magnetic phase transitions under high pressures in a quaternary rare earth transition metal arsenide oxide NdCoAsO compound that is isostructural to high temperature superconductor NdFeAsO. Four-probe electrical resistance measurements carried out in a designer diamond anvil cell show that the ferromagnetic Curie temperature and anti-ferromagnetic Neel temperature increase with an increase in pressure. High pressure x-ray diffraction studies using a synchrotron source show a structural phase transition from a tetragonal phase to a new crystallographic phase at a pressure of 23 GPa at 300 K. The NdCoAsO sample remained anti-ferromagnetic and non-superconducting to temperatures down to 10 K and to the highest pressure achieved in this experiment of 53 GPa. A P-T phase diagram for NdCoAsO is presented to a pressure of 53 GPa and low temperatures of 10 K.