Publications and Conferences

Publications

Schematic of the valley Hall effect

https://doi.org/10.1103/PhysRevLett.132.096302

Abstract

The valley Hall effect arises from valley-contrasting Berry curvature and requires inversion symmetry breaking. Here, we propose a nonlinear mechanism to generate a valley Hall current in systems with both inversion and time-reversal symmetry, where the linear and second-order charge Hall currents vanish along with the linear valley Hall current. We show that a second-order valley Hall signal emerges from the electric field correction to the Berry curvature, provided a valley-contrasting anisotropic dispersion is engineered. We demonstrate the nonlinear valley Hall effect in tilted massless Dirac fermions in strained graphene and organic semiconductors. Our Letter opens up the possibility of controlling the valley degree of freedom in inversion symmetric systems via nonlinear valleytronics.

Schematic of the Planar Hall effect in quasi-2D materials

https://link.aps.org/doi/10.1103/PhysRevLett.134.026301

Abstract: The planar Hall effect in 3D systems is an effective probe for their Berry curvature, topology, and electronic properties. However, the Berry curvature-induced conventional planar Hall effect is forbidden in 2D systems as the out-of-plane Berry curvature cannot couple to the band velocity of the electrons moving in the 2D plane. Here, we demonstrate a unique 2D planar Hall effect (2DPHE) originating from the hidden planar components of the Berry curvature and orbital magnetic moment in quasi-2D materials. We identify all planar band geometric contributions to 2DPHE and classify their crystalline symmetry restrictions. Using gated bilayer graphene as an example, we show that in addition to capturing the hidden band geometric effects, 2DPHE is also sensitive to the Lifshitz transitions. Our Letter motivates further exploration of hidden planar band geometry-induced 2DPHE and related transport phenomena for innovative applications.

Conferences

Presented a poster titled "Nonlinear Valley Hall Effect" at RPGR 2023, hosted by IISc, Bangalore—grateful that it was picked for the Best Poster Award!
Attended the Topical School of Advanced Condensed Matter Physics, organized by the Institute of Physics, Bhubaneswar (May 20–31, 2024).
Presented a poster on "Planar Hall Effect in Quasi-2D Materials" at the Engineered 2D Quantum Materials workshop, ICTS, Bengaluru (July 15–26, 2024).
Presented a poster on "Nonlinear Valley Hall Effect" at QMAT 2024, the flagship condensed matter physics meet, held at IIT Guwahati (December 20–23, 2024).