Intertwined Topological Phases in TaAs<sub>2</sub> Nanowires with Giant Magnetoresistance and Quantum Coherent Surface Transport.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40145858.
- Also identified by DOI 10.1002/adma.202418279 and PMC identifier 12271997.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Nanowires (NWs) of topological materials are emerging as an exciting platform to probe and engineer new quantum phenomena that are hard to access in bulk phase. Their quasi-1D geometry and large surface-to-bulk ratio unlock new expressions of topology and highlight surface states. TaAs<sub>2</sub>, a compensated semimetal, is a topologically rich material harboring nodal-line, weak topological insulator (WTI), C<sub>2</sub>-protected topological crystalline insulator, and Zeeman field-induced Weyl semimetal phases. We report the synthesis of TaAs<sub>2</sub> NWs in situ encapsulated in a dielectric SiO<sub>2</sub> shell, which enable to probe rich magnetotransport phenomena, including metal-to-insulator transition and strong signatures of topologically nontrivial transport at remarkably high temperatures, direction-dependent giant positive, and negative magnetoresistance, and a double pattern of Aharonov-Bohm oscillations, demonstrating coherent surface transport consistent with the two Dirac cones of a WTI surface. The SiO<sub>2</sub>-encapsulated TaAs<sub>2</sub> NWs show room-temperature conductivity up to 15 times higher than bulk TaAs<sub>2</sub>. The coexistence and susceptibility of topological phases to external stimuli have potential applications in spintronics and nanoscale quantum technology.