A strong-topological-metal material with multiple Dirac cones

TL;DR

This paper introduces Zr2Te2P, a new strong-topological-metal with multiple Dirac cones, including the first TRS-protected Dirac cones at M points, with potential for high mobility and magnetoresistance.

Contribution

It reports the discovery and characterization of Zr2Te2P as a strong-topological-metal with multiple Dirac cones, including the first observation of TRS-protected Dirac cones at M points.

Findings

Zr2Te2P is a metallic topological material with a pseudogap.

Two Dirac dispersions are predicted within the pseudogap.

ARPEs confirms the existence of TRS-protected Dirac cones at M points.

Abstract

We report a new, cleavable, strong-topological-metal, Zr2Te2P, which has the same tetradymite-type crystal structure as the topological insulator Bi2Te2Se. Instead of being a semiconductor, however, Zr2Te2P is metallic with a pseudogap between 0.2 and 0.7 eV above the fermi energy (EF). Inside this pseudogap, two Dirac dispersions are predicted: one is a surface-originated Dirac cone protected by time-reversal symmetry (TRS), while the other is a bulk-originated and slightly gapped Dirac cone with a largely linear dispersion over a 2 eV energy range. A third surface TRS-protected Dirac cone is predicted, and observed using ARPES, making Zr2Te2P the first system to realize TRS-protected Dirac cones at M points. The high anisotropy of this Dirac cone is similar to the one in the hypothetical Dirac semimetal BiO2. We propose that if EF can be tuned into the pseudogap where the Dirac dispersions exist, it may be possible to observe ultrahigh carrier mobility and large magnetoresistance in this material.