Weak antilocalization effect and triply degenerate state in Cu-doped CaAuAs

The effect of 50\% Cu doping at the Au site in the topological Dirac semimetal CaAuAs is investigated through electronic band structure calculations, electrical resistivity, and magnetotransport measurements. Electronic structure calculations a suggest broken-symmetry-driven topological phase transi...

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Bibliographic Details
Published in:arXiv.org 2022-08
Main Authors: Malick, Sudip, Ghosh, Arup, Barman, Chanchal K, Alam, Aftab, Hossain, Z, Mandal, Prabhat, Nayak, J
Format: Article
Language:English
Subjects:
Copper
Electrical resistivity
Electronic structure
Gold
Magnetoresistance
Magnetoresistivity
Phase transitions
Topology
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Summary:The effect of 50\% Cu doping at the Au site in the topological Dirac semimetal CaAuAs is investigated through electronic band structure calculations, electrical resistivity, and magnetotransport measurements. Electronic structure calculations a suggest broken-symmetry-driven topological phase transition from the Dirac to triple-point state in CaAuAs via alloy engineering. The electrical resistivity of both the CaAuAs and CaAu\(_{0.5}\)Cu\(_{0.5}\)As compounds shows metallic behavior. Nonsaturating quasilinear magnetoresistance (MR) behavior is observed in CaAuAs. On the other hand, MR of the doped compound shows a pronounced cusplike feature in the low-field regime. Such behavior of MR in CaAu\(_{0.5}\)Cu\(_{0.5}\)As is attributed to the weak antilocalization (WAL) effect. The WAL effect is analyzed using different theoretical models, including the semiclassical \(\sim\sqrt{B}\) one which accounts for the three-dimensional WAL and modified Hikami-Larkin-Nagaoka model. Strong WAL effect is also observed in the longitudinal MR, which is well described by the generalized Altshuler-Aronov model. Our study suggests that the WAL effect originates from weak disorder and the spin-orbit coupled bulk state. Interestingly, we have also observed the signature of chiral anomaly in longitudinal MR, when both current and field are applied along the \(c\) axis. The Hall resistivity measurements indicate that the charge conduction mechanism in these compounds is dominated by the holes with a concentration \(\sim\)10\(^{20}\) cm\(^{-3}\) and mobility \(\sim 10^2\) cm\(^2\) V\(^{-1}\) S\(^{-1}\).
ISSN:2331-8422
DOI:10.48550/arxiv.2208.06208