Local and Tunable Geometric Phase of Dirac Fermions in a Topological Junction

TL;DR

This paper introduces a tunable geometric phase for Dirac fermions in topological junctions, revealing new topological properties and enabling novel electronic devices based on topological charge and spin transport.

Contribution

It uncovers a local, tunable geometric phase in Dirac fermions during scattering, linking topological order detection to a new bulk-edge correspondence.

Findings

Geometric phase is experimentally tunable to arbitrary values.

The phase reveals topological aspects of Dirac fermion scattering.

Implications for designing topological electronic devices.

Abstract

We discover a new type of geometric phase of Dirac fermions in solids, which is an electronic analogue of the Pancharatnam phase of polarized light. The geometric phase occurs in a local and nonadiabatic scattering event of Dirac fermions at a junction, unveiling topological aspects of scattering of chiral particles, and it is experimentally tunable to an arbitrary value. It provides a unique approach of detecting the topological order of the insulator in a metal-insulator junction of Dirac fermions, establishing new bulk-edge correspondence. The geometric phase also modifies the fundamental quantization rule of Dirac fermions, suggesting topological devices with nontrivial charge and spin transport such as a topological wave guide and a topological transistor.