First-principles study of pressure-induced magnetic phase transitions in ternary iron selenide K$_{0.8}$Fe$_{1.6}$Se$_2$

TL;DR

This study uses first-principles calculations to explore how pressure affects the electronic and magnetic phases of K$_{0.8}$Fe$_{1.6}$Se$_2$, revealing two phase transitions from magnetic semiconducting to metallic and then to non-magnetic states.

Contribution

It provides a detailed theoretical analysis of pressure-induced magnetic phase transitions in K$_{0.8}$Fe$_{1.6}$Se$_2$, clarifying experimental observations.

Findings

Transition from blocked checkerboard AFM semiconducting to collinear AFM metallic at ~12 GPa

Transition from collinear AFM metallic to non-magnetic metallic at ~25 GPa

Pressure induces significant changes in magnetic and electronic structures

Abstract

We have studied the pressure effect on electronic structures and magnetic orders of ternary iron selenide K$_{0.8}$Fe$_{1.6}$Se$_2$ by the first-principles electronic structure calculations. At low pressure, the compound is in the blocked checkerboard antiferromagnetic (AFM) semiconducting phase, as observed by the neutron scatting measurements. Applying pressure induces two phase transitions, first from the blocked checkerboard AFM semiconducting phase to a collinear AFM metallic phase around 12 GPa, and then to a non-magnetic metallic phase around 25 GPa, respectively. Our results help to clarify the recent experimental measurements under pressure.