Non-collinearity and spin frustration in the itinerant kagome ferromagnet Fe3Sn2

TL;DR

This paper reveals that Fe3Sn2, previously thought to be a simple ferromagnet, is actually a frustrated itinerant ferromagnet with a non-collinear spin structure and complex magnetic interactions, which enhances its potential for spintronics applications.

Contribution

The study demonstrates that Fe3Sn2 exhibits non-collinear spin structures and spin frustration, challenging previous assumptions and highlighting its unique magnetic properties among kagome ferromagnets.

Findings

Fe3Sn2 is a frustrated ferromagnet with non-collinear spins.

Re-entrant spin glass transition at ~80 K.

Enhanced anomalous Hall effect potential due to magnetic structure.

Abstract

Frustrated itinerant ferromagnets, with non-collinear static spin structures, are an exciting class of material as their spin chirality can introduce a Berry phase in the electronic scattering and lead to exotic electronic phenomena such as the anomalous Hall effect (AHE). This study presents a reexamination of the magnetic properties of Fe$_3$Sn$_2$, a metallic ferromagnet, based on the 2-dimensional kagome bilayer structure. Previously thought of as a conventional ferromagnet, we show using a combination of SQUID measurements, symmetry analysis and powder neutron diffraction, that Fe$_3$Sn$_2$ is a frustrated ferromagnet with a temperature-dependent non-collinear spin structure. The complexity of the magnetic interactions is further evidenced by a re-entrant spin glass transition ($T_f\simeq80$\,K) at temperatures far below the main ferromagnetic transition ($T\mathrm{_C}$ = 640\,K). Fe$_3$Sn$_2$ therefore provides a rare example of a frustrated itinerant ferromagnet. Further, as well as being of great fundamental interest our studies highlight the potential of Fe$_3$Sn$_2$ for practical application in spintronics technology, as the AHE arising from the ferromagnetism in this material is expected to be enhanced by the coupling between the conduction electrons and the non-trivial magnetic structure over an exceptionally wide temperature range.