Manifestation of the Berry curvature in Co2TiSn Heusler films

TL;DR

This study investigates the Berry curvature effects in Co2TiSn Heusler films, demonstrating experimental and theoretical agreement on anomalous Hall conductivity linked to topological features, advancing understanding of spintronics applications.

Contribution

It provides the first combined experimental and theoretical analysis of Berry curvature and anomalous Hall effect in epitaxial Co2TiSn films, highlighting the role of nodal lines and symmetry reduction.

Findings

Measured Hall conductivity agrees with Berry curvature calculations.

Skew scattering influences deviations in Hall effect measurements.

Electronic structure matches theoretical density of states.

Abstract

Various Co2 based Heusler compounds are predicted to be Weyl materials. These systems with broken symmetry possess a large Berry curvature, and introduce exotic transport properties. The present study on epitaxially grown Co2TiSn films is an initial approach to understand and explore this possibility. The anomalous Hall effect in the well-ordered Co2TiSn films has been investigated both experimentally and theoretically. The measured Hall conductivity is in good agreement to the calculated Berry curvature. Small deviations between them are due to the influence of skew scattering on the Hall effect. From theoretical point of view, the main contribution to the anomalous Hall effect originates from slightly gapped nodal lines, due to a symmetry reduction induced by the magnetization. It has been found that only part of the nodal lines contributed near to the anomalous Hall conductivity at a fixed Fermi energy which can be explained from a magnetic symmetry analysis. Furthermore, from hard x-ray photoelectron spectroscopy measurements, we establish the electronic structure in the film that is comparable to the theoretical density of states calculations. The present results provide deeper insight into the spintronics from the prospect of topology.