Stabilizing Topological States in ZrTe₅ from First-Principles Defect Physics.

Abstract

ZrTe₅, a topological material with tunable quantum phenomena, faces conflicting experimental results largely due to sample quality variations. Despite intense interest in stabilizing its quantum states, a clear strategy for controlling intrinsic defects has remained elusive. Through first-principles investigations of intrinsic point defects, we identify a practical route to achieving stable and ideal topological characteristics in ZrTe₅. Our study reveals that donor-like Zr interstitials and acceptor-like Te vacancies compete to govern the Fermi level, with defect density determining topological phases. We theoretically propose increasing the Te/Zr ratio during growth to suppress intrinsic defects, stabilizing ZrTe₅ in a nearly ideal weak topological insulator state. These predictions are supported by experimental measures, exhibiting a reduction in bulk conduction with increasing Te/Zr ratio. These findings offer clear guidance for defect control and sample optimization, enabling the robust and reproducible realization of topological quantum states in ZrTe₅ for future quantum applications.