Berry curvature dipole and nonlinear Hall effect in two-dimensional <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Nb</mml:mi><mml:mrow><mml:mn>2</mml:mn><mml:mi>n</mml:mi><mml:mo>+</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi>Si</mml:mi><mml:mi>n</mml:mi></mml:msub><mml:msub><mml:mi>Te</mml:mi><mml:mrow><mml:mn>4</mml:mn><mml:mi>n</mml:mi><mml:mo>+</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>
Yiwei Zhao, Jin Cao, Zeying Zhang, Si Li, Yan Li, Fei Ma, Shengyuan A. Yang
Abstract
Recent experiments have demonstrated interesting physics in a family of two-dimensional composition-tunable materials ${\mathrm{Nb}}_{2n+1}{\mathrm{Si}}_{n}{\mathrm{Te}}_{4n+2}$. Here we show that, owing to their intrinsic low symmetry, metallic nature, tunable composition, and ambient stability, these materials offer a good platform for studying the Berry curvature dipole (BCD) and nonlinear Hall effect. Using first-principles calculations, we find that the BCD exhibits pronounced peaks in monolayer ${\mathrm{Nb}}_{3}{\mathrm{SiTe}}_{6}$ (the $n=1$ case). Its magnitude decreases monotonically with $n$ and completely vanishes in the $n\ensuremath{\rightarrow}\ensuremath{\infty}$ limit. This variation manifests a special hidden dimensional crossover of the low-energy electronic states in this system. The resulting nonlinear Hall response from the BCD in these materials is discussed. Our work reveals pronounced geometric quantities and nonlinear transport physics in ${\mathrm{Nb}}_{2n+1}{\mathrm{Si}}_{n}{\mathrm{Te}}_{4n+2}$ family materials, which should be readily detected in experiment.