Low-temperature phase diagram of Fe1+yTe

TL;DR

This study investigates the structural phase transitions of Fe1+yTe at low temperatures, revealing a two-step transition and a revised phase diagram through combined diffraction and thermodynamic measurements.

Contribution

It provides a detailed low-temperature phase diagram of Fe1+yTe, highlighting the competition between orthorhombic and monoclinic phases near a tricritical point.

Findings

Two-step structural and magnetic phase transitions occur within 0.11 ≤ y ≤ 0.13.

Transitions are sluggish, indicating strong competition between phases.

Revised temperature-composition phase diagram for Fe1+yTe.

Abstract

We used low-temperature synchrotron x-ray diffraction to investigate the structural phase transitions of Fe1+yTe in the vicinity of a tricitical point in the phase diagram. Detailed analysis of the powder diffraction patterns and temperature dependence of the peak-widths in Fe1+yTe showed that two-step structural and magnetic phase transitions occur within the compositional range 0.11 $\leq y \leq $ 0.13. The phase transitions are sluggish indicating a strong competition between the orthorhombic and the monoclinic phases. We combine high-resolution diffraction experiments with specific heat, resistivity, and magnetization measurements and present a revised temperature-composition phase diagram for Fe1+yTe.