Magnetotransport as diagnostic of spin reorientation: kagome ferromagnet as a case study

TL;DR

This study investigates the spin reorientation in kagome ferromagnet Fe3Sn2 using anisotropic magnetoresistivity, revealing domain evolution, phase coexistence, and an unreported electronic transition around 40 K.

Contribution

It provides detailed insight into magnetic domain behavior during spin reorientation and introduces the use of anisotropic magnetoresistivity as a diagnostic tool in this context.

Findings

Magnetic domains evolve with temperature during reorientation.

Coexistence of out-of-plane and in-plane phases indicates a first-order transition.

An unreported electronic transition occurs around 40 K.

Abstract

While in most ferro or antiferromagnetic materials there is a unique crystallographic direction, including crystallographically equivalent directions, in which the moments like to point due to spin-orbit coupling, in some, the direction of the spin reorients as a function of a certain physical parameter such as temperature, pressure etc. Fe3Sn2 is a kagome ferromagnet with an onset of ferromagnetism below 650 K, and undergoes a spin reorientation near 150 K. While it is known that the moments in Fe3Sn2 point perpendicular to the kagome plane at high temperatures and parallel to the kagome plane at low temperatures, how the distribution of the magnetic domains in the two different spin orientations evolve throughout the spin reorientation is not well known. Furthermore, while there have been various reports on the magnetotransport properties in the Hall configuration, the angular dependence of magnetoresistance has not been studied so far. In this paper, we have examined the spin reorientation by using anisotropic magnetoresistivity in detail, exploiting the dependence of the resistivity on the direction between magnetization and applied current. We are able to determine the distribution of the magnetic domains as a function of temperature between 360 K to 2 K and the reorientation transition to peak at 120 K. We discover that both out of plane and in plane phases coexist at temperatures around the spin reorientation, indicative of a first order transition. Although the volume of the magnetic domains in the different phases sharply changes at the spin reorientation transition, the electronic structure for a specific magnetization is not influenced by the spin reorientation. In contrast, we observe an electronic transition around 40 K, hitherto unreported, and reflected in both the zero-field resistivity and anisotropic resistivity.