Strongly Enhanced Berry Dipole at Topological Phase Transitions in BiTeI

FACIO, JORGE I.; EFREMOV, DMITRI; KOEPERNIK, KLAUS; YOU, JHIH-SHIH; SODEMANN, INTI; VAN DEN BRINK, JEROEN

PHYSICAL REVIEW LETTERS

American Physical Society

Año: 2018 vol. 121

0031-9007

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 which exhibits a pressure-driven phase transition between topological and trivial insulators in three dimensions. We demonstrate that this transition, which proceeds through an intermediate Weyl semimetallic 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 Berry 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 2 orders of magnitude.