High pressure diffraction studies on Ca2RuO4

TL;DR

This study investigates the structural and magnetic changes in Ca2RuO4 under high pressure, revealing a first-order phase transition, structural modifications, and magnetic order rearrangements using diffraction techniques.

Contribution

It provides new insights into pressure-induced phase transitions and magnetic behavior in Ca2RuO4 through comprehensive diffraction analysis.

Findings

First order phase transition at 0.5 GPa with phase coexistence

Discontinuous change in RuO6-Octahedra tilt and rotation

Disappearance of tilt above 5.5 GPa leading to higher symmetry

Abstract

We studied the crystal and magnetic structure of Ca2RuO4 by different diffraction techniques under high pressure. The observed first order phase transition at moderate pressure (0.5 GPa) between the insulating phase and the metallic high pressure phase is characterized by a broad region of phase coexistence. The following structural changes are observed as function of pressure: a) a discontinuous change of both the tilt and rotation angle of the RuO6-Octahedra at this transition, b) a gradual decrease of the tilt angle in the high pressure phase (p>0.5 GPa) and c) the disappearance of the tilt above 5.5GPa leading to a higher symmetry structure. By single crystal neutron diffraction at low temperature, the ferromagnetic component of the high pressure phase and a rearrangement of antiferromagnetic order in the low pressure phase was observed.