Phonon anomalies predict superconducting Tc for AlB2-type structures

Alarco, Jose A., Talbot, Peter C., & Mackinnon, Ian D.R. (2015) Phonon anomalies predict superconducting Tc for AlB2-type structures. Physical Chemistry Chemical Physics, 17, pp. 25090-25099.

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Abstract

We show that the well-known Kohn anomaly predicts Tc for ordered AlB2-type structures. We use ab initio Density Functional Theory to calculate phonon dispersions for Mg1-xAlxB2 compositions and identify a phonon anomaly with magnitude that predicts experimental values of Tc for all x. Key features of these anomalies correlate with the electronic structure of Mg1-xAlxB2. This approach predicts Tc for other known AlB2-type structures as well as new compositions. We predict that Mg0.5Ba0.5B2 will show Tc = 63.6 ± 6.6 K. Other forms of the Mg1-xBaxB2 series will also be superconductors when successfully synthesised. Our calculations predict that the end-member composition, BaB2, is likely to show a Tc significantly higher than currently achieved by other diborides although an applied pressure ~16 GPa may be required to stabilise the structure.

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ID Code: 87310
Item Type: Journal Article
Refereed: Yes
Additional Information: First published online: 28 Aug 2015
Keywords: Density Functional Theory, Magnesium Diboride, Phonon Anomaly, Superconducting transition temperature, Electronic band structure
DOI: 10.1039/C5CP04402B
ISSN: 1463-9076
Subjects: Australian and New Zealand Standard Research Classification > PHYSICAL SCIENCES (020000) > CONDENSED MATTER PHYSICS (020400) > Condensed Matter Modelling and Density Functional Theory (020403)
Australian and New Zealand Standard Research Classification > PHYSICAL SCIENCES (020000) > CONDENSED MATTER PHYSICS (020400) > Electronic and Magnetic Properties of Condensed Matter; Superconductivity (020404)
Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > THEORETICAL AND COMPUTATIONAL CHEMISTRY (030700)
Divisions: Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Current > Institutes > Institute for Future Environments
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2015 Royal Society of Chemistry
Copyright Statement: This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.
Deposited On: 10 Sep 2015 23:28
Last Modified: 11 Jan 2016 04:49

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