Orbital Fingerprint of Topological Fermi Arcs in a Weyl Semimetal

TL;DR

This study combines experimental and theoretical methods to analyze the orbital texture of Fermi arcs in the Weyl semimetal TaP, revealing how orbital degrees of freedom influence topological surface-bulk connectivity.

Contribution

It provides a detailed orbital-level understanding of Fermi arcs in TaP, linking orbital texture switches to topological classification, which was previously not well understood.

Findings

Orbital texture switches at Weyl nodes observed.

Orbital degrees of freedom mediate surface-bulk connectivity.

Enhanced topological classification of surface states achieved.

Abstract

The monopnictides TaAs and TaP are well-established Weyl semimetals. Yet, a precise assignment of Fermi arcs, accomodating the predicted chiral charge of the bulk Weyl points, has been difficult in these systems, and the topological character of different surface features in the Fermi surface is not fully understood. Here, employing a joint analysis from linear dichroism in angle-resolved photoemission and first-principles calculations, we unveil the orbital texture on the full Fermi surface of TaP(001). We observe pronounced switches in the orbital texture at the projectedWeyl nodes, and show how they facilitate a topological classification of the surface band structure. Our findings establish a critical role of the orbital degrees of freedom in mediating the surface-bulk connectivity in Weyl semimetals.