Normal and intrinsic anomalous Hall effect in Nb1-yFe2+y

TL;DR

This study investigates the normal and anomalous Hall effects in Nb1-yFe2+y, revealing intrinsic contributions and complexities in modeling the Hall effect in itinerant antiferromagnets.

Contribution

It provides the first detailed analysis of the intrinsic anomalous Hall effect in Nb1-yFe2+y, highlighting the role of Berry-phase contributions and the need for advanced models.

Findings

Positive normal Hall effect dominates at high temperatures.

Intrinsic (Berry-phase) anomalous Hall contribution is constant below TC.

Additional Hall resistivity contributions complicate analysis in some samples.

Abstract

The Hall effect on selected samples of the dilution series Nb1-yFe2+y is studied. Normal and anomalous contributions are observed, with positive normal Hall effect dominating at high temperatures. Consistent analysis of the anomalous contribution is only possible for Fe-rich Nb0.985Fe2.015 featuring a ferromagnetic ground state. Here, a positive normal Hall coefficient is found at all temperatures with a moderate maximum at the spin-density-wave transition. The anomalous Hall effect is consistent with an intrinsic (Berry-phase) contribution which is constant below the ordering temperature TC and continuously vanishes above TC. For stoichiometric NbFe2 and Nb-rich Nb1.01Fe1.99 - both having a spin-density-wave ground state - an additional contribution to the Hall resistivity impedes a complete analysis and indicates the need for more sophisticated models of the anomalous Hall effect in itinerant antiferromagnets.