Tunable Giant Berry Curvature Dipole in Two-Dimensional Xenes

The anomalous Hall effect in time-reversal symmetry broken systems is underpinned by the concept of Berry curvature in band theory. However, recent experiments [1] reveal that the nonlinear Hall effect can be observed in non-magnetic systems without an external magnetic field [2]. The emergence of the nonlinear Hall effect under time-reversal symmetric conditions can be well-explained in terms of Berry curvature dipole arising from inversion symmetry breaking [3]. Using realistic tight-binding models and symmetry analyses, we have discovered that the combined effect of transverse electric field and strain leads to a giant Berry curvature dipole in the elemental buckled honeycomb lattices, i.e., Xenes [4]. The topology of the electronic wavefunction switches from the band-inverted quantum spin Hall state to an electric field-driven normal insulating one about the gapless point, which is further accompanied by an enhanced and switchable Berry curvature dipole near the Fermi level. Furthermore, strain engineering on puckered phosphorene layers grown on a suitable substrate exhibits a large Berry curvature dipole [5]. Our results predict an externally controllable nonlinear Hall effect in a new class of elemental systems that can be experimentally verified.

[1] Ma et al., Nature 565, 337 (2019).

[2] Du et al., Nature Reviews Physics, 1 (2021).

[3] Sodemann et al. Physical review letters 115, 216806 (2015).

[4] Bandyopadhyay et al. 2D Materials 9, 035013 (2022).

[5] Bandyopadhyay et al. (under review, 2023)