Multi-k magnetic structure and large anomalous Hall effect in candidate magnetic Weyl semimetal NdAlGe

TL;DR

This study uncovers complex magnetic ordering and a significant anomalous Hall effect in NdAlGe, linking electronic structure features like Weyl nodes and Fermi surface nesting to its transport properties.

Contribution

It reveals the coexistence of complex magnetic structures and large anomalous Hall conductivity in NdAlGe, highlighting the role of Weyl nodes and Fermi surface nesting in this non-centrosymmetric magnetic semimetal.

Findings

Large anomalous Hall conductivity of 430 Ω^-1cm^-1

Complex magnetic structure with incommensurate and ferrimagnetic states

Weyl nodes near the Fermi surface linked to transport properties

Abstract

The magnetic structure, magnetoresistance, and Hall effect of non-centrosymmetric magnetic semimetal NdAlGe are investigated revealing an unusual magnetic state and anomalous transport properties that are associated with the electronic structure of this non-centrosymmetric compound. The magnetization and magnetoresistance measurements are both highly anisotropic and indicate an Ising-like magnetic system. The magnetic structure is complex in that it involves three magnetic ordering vectors including an incommensurate spin density wave and commensurate ferrimagnetic state in zero field. We have discovered a large anomalous Hall conductivity that reaches = 430 {\Omega}-1cm-1 implying that it originates from an intrinsic Berry curvature effect stemming from Weyl nodes found in the electronic structure. These electronic structure calculations indicate the presence of nested Fermi surface pockets with nesting wave vectors similar to the measured magnetic ordering wavevector and the presence of Weyl nodes in proximity to the Fermi surface. We associate the incommensurate magnetic structure with the large anomalous Hall response to be the result of the combination of Fermi surface nesting and the Berry curvature associated with Weyl nodes.