Pressure-Modulated Structural and Magnetic Phase Transitions in Two-Dimensional FeTe: Tetragonal and Hexagonal Polymorphs

TL;DR

This study explores how hydrostatic pressure induces structural and magnetic phase transitions in two-dimensional FeTe with tetragonal and hexagonal structures, revealing distinct magnetic behaviors and phase diagrams crucial for spintronics applications.

Contribution

It provides a systematic comparison of pressure effects on 2D tetragonal and hexagonal FeTe, mapping their phase diagrams and revealing pressure-induced magnetic transitions.

Findings

t-FeTe transitions from antiferromagnetic to ferromagnetic at ~3 GPa

h-FeTe retains ferromagnetic order up to 15 GPa

Detailed P-T phase diagrams for both polymorphs are established.

Abstract

Two-dimensional (2D) Fe-chalcogenides with rich structures, magnetisms and superconductivities are highly desirable to reveal the torturous transition mechanism and explore their potential applications in spintronics and nanoelectronics. Hydrostatic pressure can effectively stimulate novel phase transitions between various ordered states and to plot the seductive phase diagram. Herein, the structural evolution and transport characteristics of 2D FeTe were systematically investigated under extreme conditions through comparing two distinct symmetries, i.e., tetragonal (t-) and hexagonal (h-) FeTe. We found that 2D t-FeTe presented the pressure-induced transition from antiferromagnetic to ferromagnetic states at ~ 3 GPa, corresponding to the tetragonal collapse of layered structure. Contrarily, ferromagnetic order of 2D h-FeTe was retained up to 15 GPa, evidently confirmed by electrical transport and Raman measurements. Furthermore, the detailed P-T phase diagrams of both 2D t-FeTe and h-FeTe were mapped out with the delicate critical conditions. We believe our results can provide a unique platform to elaborate the extraordinary physical properties of Fe-chalcogenides and further to develop their practical applications.