Tuning of Berry Curvature Dipole in TaAs slabs: An effective Route to Enhance Nonlinear Hall Response

TL;DR

This paper demonstrates that stacking layers of TaAs can significantly enhance the Berry curvature dipole, thereby boosting the nonlinear Hall response, by selectively tuning Weyl point contributions and reducing cancellation effects.

Contribution

The study introduces a layer-stacking strategy to effectively increase the Berry curvature dipole in TaAs slabs, surpassing bulk limitations and enabling targeted control of Weyl point contributions.

Findings

8-layer TaAs slabs have a BCD much larger than bulk near the Fermi level.

Layer stacking can selectively enhance BCD by tuning Weyl point contributions.

Quantum confinement suppresses unwanted Weyl point contributions, reducing cancellation effects.

Abstract

In materials without inversion symmetry, Berry curvature dipole (BCD) arises from the uneven distribution of Berry curvature in momentum space. This leads to nonlinear anomalous Hall effects even in systems with preserved time-reversal symmetry. A key goal is to engineer systems with prominent BCD near the Fermi level. Notably, TaAs, a type-I Weyl semimetal, exhibits substantial Berry curvature but a small BCD around the Fermi level. In this study, we employed first-principles methods to comprehensively investigate the BCD in TaAs. Our findings reveal significant cancellation effects not only within individual Weyl points but crucially, among distinct Weyl point pairs in bulk TaAs. We propose a strategic approach to enhance the BCD in TaAs by employing a layer-stacking technique. This greatly amplifies the BCD compared to the bulk material. By tuning the number of slab layers, we can selectively target specific Weyl point pairs near the Fermi level, while quantum confinement effects suppress contributions from other pairs, mitigating cancellation effects. Especially, the BCD of an 8-layer TaAs slab surpasses the bulk value near the Fermi level by orders of magnitude.