Enhanced spin ordering temperature in ultrathin FeTe films grown on a topological insulator

TL;DR

This study reveals that ultrathin FeTe films on a topological insulator exhibit a higher spin ordering temperature than bulk FeTe, due to interface effects and reduced excess Fe, which is significant for superconductivity research.

Contribution

It demonstrates enhanced spin order stability in ultrathin FeTe films on Bi_2Te_3, highlighting interface effects and reduced excess Fe as key factors.

Findings

Spin order persists at higher temperatures than bulk FeTe.

Enhanced stability attributed to decreased excess Fe and interface effects.

Relevance to coexistence of superconductivity and spin order.

Abstract

We studied the temperature dependence of the diagonal double-stripe spin order in one and two unit cell thick layers of FeTe grown on the topological insulator Bi_2Te_3 via spin-polarized scanning tunneling microscopy. The spin order persists up to temperatures which are higher than the transition temperature reported for bulk Fe_1+yTe with lowest possible excess Fe content y. The enhanced spin order stability is assigned to a strongly decreased y with respect to the lowest values achievable in bulk crystal growth, and effects due to the interface between the FeTe and the topological insulator. The result is relevant for understanding the recent observation of a coexistence of superconducting correlations and spin order in this system.