Anomalous shift in scattering from topological nodal-ring semimetals

TL;DR

This paper reveals that the anomalous spatial shift during electron reflection from topological nodal-ring semimetals encodes topological information, providing a new method to probe their topological band structures.

Contribution

It demonstrates that the scattering shift is enhanced by nodal rings and directly relates to their topological charge, offering a novel physical signature for topological phase transitions.

Findings

Shift magnitude is enhanced by nodal rings.

Shift vectors reveal ring geometry.

Shift circulation encodes topological charge.

Abstract

An electron beam may experience an anomalous spatial shift during an interface scattering process. Here, we investigate this phenomenon for reflection from mirror-symmetry-protected nodal-ring semimetals, which are characterized by an integer topological charge $\chi_h$. We show that the shift is generally enhanced by the presence of nodal rings, and the ring's geometry can be inferred from the profile of shift vectors in the interface momentum plane. Importantly, the anomalous shift encodes the topological information of the ring, where the circulation of the shift vector field $\kappa_s$ over a semicircle is governed by the topological charge, with a simple relationship: $\kappa_s=-2\pi \chi_h$. Furthermore, we demonstrate that the shift and its circulation reflect distinct features of topological phase transitions of the charged rings. This study uncovers a novel physical signature of topological nodal rings and positions anomalous scattering shifts as a powerful tool for probing topological band structures.