Effect of Spin Fluctuations on Magnetoresistance and Anomalous Hall Effect in the Chiral Magnet Co8Zn8Mn4

TL;DR

This study investigates how spin fluctuations influence magnetoresistance and the anomalous Hall effect in Co8Zn8Mn4, revealing skew-scattering as a key mechanism and highlighting the role of spin fluctuations in chiral magnets with skyrmions.

Contribution

It demonstrates that spin fluctuations are the primary source of skew-scattering in Co8Zn8Mn4, challenging the conventional understanding that skew-scattering dominates only in high-conductivity materials.

Findings

Negative magnetoresistance observed from 50K to 300K

Spin fluctuations cause deviation from linear MR curves at higher temperatures

Skew-scattering mechanism dominates the anomalous Hall effect

Abstract

The beta Mn type Co-Zn-Mn alloys have seized significant attention due to their ability to host skyrmions at room temperature. Here we analyse the unconventional magneto-transport properties of Co8Zn8Mn4 single crystals with a Curie temperature of 275 K. A negative magnetoresistance is obtained over a wide temperature range of 50K to 300K. The deviation of the isothermal magnetoresistance (MR) curves from linearity to non-linearity as one approaches higher temperatures points towards the transition from the dominance of magnons to spin fluctuations. In the paramagnetic phase, the change in the shape of the MR curve has been explained using the Khosla and Fischer model. The relationship between the anomalous Hall effect (AHE) and longitudinal resistivity reveals the dominance of the skew-scattering mechanism, which is inexplicable based on the theories of semi-classical magneto-transport. We experimentally determine that the spin fluctuation is the source of the skew-scattering mechanism in Co8Zn8Mn4. In general skew-scattering mechanisms predominate in compounds with high conductivity, but our findings demonstrate that this is not always the case and that other aspects also require equal consideration. Our work throws new light on the predominant scattering mechanism in chiral magnets with skyrmionics phase at low conductivity.