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Exploring the Interplay between Structure and Electronic Behavior across Pressure-Induced Isostructural and Structural Transitions in Weyl-Type Semimetal NbAs

Authors :
João E. F. S. Rodrigues
Emin Mijit
Angelika D. Rosa
Laura Silenzi
Nodoka Hara
Catalin Popescu
José A. Alonso
Tetsuo Irifune
Zhiwei Hu
Andrea Di Cicco
Source :
Crystals, Vol 14, Iss 7, p 578 (2024)
Publication Year :
2024
Publisher :
MDPI AG, 2024.

Abstract

NbAs is a Weyl semimetal and belongs to the group of topological phases that exhibit distinct quantum and topological attributes. Topological phases have a fundamentally different response to external perturbations, such as magnetic fields. To obtain insights into the response of such phases to pressure, we conducted a comprehensive study on the pressure-induced electronic and structural transitions in NbAs. We used micro-X-ray diffraction (XRD) and micro-X-ray spectroscopy (XAS) techniques to elucidate the changes at different atomic and electronic length scales (local, medium, and bulk) as combined with theoretical calculations. High-pressure XRD measurements revealed a rather common compression behavior up to ~12 GPa that could be fitted to an equation of state formalism with a bulk modulus of K0= 179.6 GPa. Complementary Nb K-edge XAS data unveiled anomalies at pressure intervals of ~12–15 and ~25–26 GPa in agreement with previous literature data from XRD studies. We attribute these anomalies to a previously reported topological Lifshitz transition and the tetragonal-to-hexagonal phase transition, respectively. Analysis of EXAFS results revealed slight changes in the mean next-nearest neighbor distance Nb–As(1) (~2.6 Å) at ~15 GPa, while the second nearest neighboring bond Nb–Nb(1) (~3.4 Å) shows a pronounced anomaly. This indicates that the electronic changes across the Lifshitz transition are accommodated first in the medium-range atomic structure and then at the local range and bulk. The variances of these bonds show anomalous but progressive evolutions close to the tetragonal-to-hexagonal transition at ~25 GPa, which allowed us to derive the evolution of vibration properties in this material. We suggest a prominent displacive character of the I41md→P6¯m2 transition facilitated by phonon modes.

Details

Language :
English
ISSN :
20734352
Volume :
14
Issue :
7
Database :
Directory of Open Access Journals
Journal :
Crystals
Publication Type :
Academic Journal
Accession number :
edsdoj.9e4f32ad10474690dcb12838c717ef
Document Type :
article
Full Text :
https://doi.org/10.3390/cryst14070578