Strongly Enhanced Berry Dipole at Topological Phase Transitions in BiTeI

Abstract

Transitions between topologically distinct electronic states have been predicted in different classes of materials and observed in some. A major goal is the identification of measurable properties that directly expose the topological nature of such transitions. Here we focus on the giant-Rashba material bismuth tellurium iodine (BiTeI) which exhibits a pressure-driven phase transition between topological and trivial insulators in threedimensions. We demonstrate that this transition, which proceeds through an intermediate Weyl semi-metallic state, is accompanied by a giant enhancement of the Berry curvature dipole which can be probed in transport and optoelectronic experiments. From first-principles calculations, we show that the Berrry-dipole -a vector along the polar axis of this material-has opposite orientations in the trivial and topological insulating phases and peaks at the insulator-to-Weyl critical points, at which the nonlinear Hall conductivity can increase by over two orders of magnitude.

Prediction of ferroelectricity-driven Berry curvature enabling charge- and spin-controllable photocurrent in tin telluride monolayers

“…20,21 Since level crossing can generate a singular BC distribution, topological materials that possess small inverted band gaps or band crossings have been mostly studied as efficient platforms for hosting a large BC dipole. [20][21][22][23][24][25][26] For instance, a small-gap quantum spin Hall WTe2 monolayer shows a large inter-band BC and its dipole is manipulated by an external electric field, resulting in the circular photogalvanic effect. 20 Tilted Weyl semimetals and pressurized BiTeI that is driven towards the topological phase transition regime also exhibit a large enhancement in the intra-band BC dipole, leading to the nonlinear Hall effect by generating a transverse photocurrent under linearly polarized light.…”

“…20 Tilted Weyl semimetals and pressurized BiTeI that is driven towards the topological phase transition regime also exhibit a large enhancement in the intra-band BC dipole, leading to the nonlinear Hall effect by generating a transverse photocurrent under linearly polarized light. 24,25 Despite the large BC dipoles in these topological materials, the prominent nonlinear optical properties are available only in response to low-frequency fields due to the small size of the band gap and the sub-band energy splitting.…”

“…As a result, the reversal of the photon helicity inverts the direction of the charge current only, remaining the spin current invariant. In addition to the time-dependent DFT calculations and the symmetry argument, we develop an analytic formalism for the charge and spin photogalvanic currents to verify their ferroelectric origin and the manoeuvrability by the photon handedness and the ferroelectricity [see Supplementary Eqs (21),(22),(24),. and(25)].…”

Berry Curvature Dipole in Strained Graphene: A Fermi Surface Warping Effect

“…Finally, different non-centrosymmetric three-dimensional materials have been proposed to feature sizable Berry curvature dipoles. These include the topological crystalline insulator SnTe [18], which undergoes a ferroelectric distorsion at low temperatures [19], time-reversal symmetric Weyl semimetals in the TaAs materials class [8], as well as the giant Rashba material BiTeI [20].…”

Probing quantum criticality using nonlinear Hall effect in a metallic Dirac system

“…In the proximity of the line of strongly coupled QCPs, given by Eq. (12), which, as we show, governs the behavior of the tDFs at the QPT, the nonlinear conductivity picks up a correction given by…”