Title: Non-Linear Hall Effect in Flatlands and Chiral Crystals
Speaker: Prof. Awadhesh Narayan, Indian Institute of Science
Abstract: In recent years, it has been discovered that inversion symmetry broken systems can exhibit non-linear Hall effects even under time-reversal symmetric conditions [1]. The underlying quantum objects leading to this phenomena are the moments of the Berry curvature, termed the Berry curvature multipoles. This opens up avenues for exploring fundamental physics and possible applications [2,3]. However, despite such promise, the Berry curvature multipole induced non-linear Hall effect has been experimentally realized only in a handful of materials. It is, therefore, of vital importance to find materials with large and controllable Berry curvature multipoles.
In this talk, I will give examples from our work where such a controllable Berry curvature dipole has been predicted. First, we propose a giant non-linear Hall effect in the elemental buckled honeycomb lattices -- silicene, germanene, and stanene [4]. We show that the Berry curvature dipole is tunable by a transverse electric field which breaks inversion symmetry. We demonstrate that the electric field induced topological phase transitions are associated with a giant Berry curvature dipole near the critical field. Next, I will present chiral systems as promising platforms to study the non-linear Hall effects [5]. We use state-of-the-art first-principles computations, in conjunction with symmetry analyses, to explore a variety of chiral material classes. We demonstrate that the two enantiomeric pairs exhibit an opposite sign of the Berry curvature dipole, which may enable their identification via a non-linear Hall response.
[1] I. Sodemann and L. Fu, Phys. Rev. Lett. 115, 216806 (2015).
[2] Z. Du, H.-Z. Lu, and X. Xie, Nature Reviews Physics 3, 744 (2021).
[3] A. Bandyopadhyay, N. B. Joseph, and A. Narayan, Materials Today Electronics 8, 100101 (2024).
[4] A. Bandyopadhyay, N. B. Joseph, and A. Narayan, 2D Materials 9, 035013 (2022).
[5] N. B. Joseph, A. Bandyopadhyay, and A. Narayan, Chemistry of Materials 6, 8602 (2024).