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Anomalous low-temperature saturation effects and negative thermal expansion in the c-axis of highly oriented pyrolytic graphite at the magic angle

Taallah, Ayoub, Shuai, Gao, Odunmbaku, Omololu, Corrias, Anna, Boi, Filippo (2020) Anomalous low-temperature saturation effects and negative thermal expansion in the c-axis of highly oriented pyrolytic graphite at the magic angle. Materials Research Express, . ISSN 2053-1591. (doi:10.1088/2053-1591/ab6890) (KAR id:79522)

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https://doi.org/10.1088/2053-1591%2Fab6890

Abstract

We report a novel T-XRD and Rietveld-refinement investigation of pyrolytic-graphite samples with high degree of graphene-layer-orientation and misfit-rotational-angle of ~ 0.8o in the T-range from 12K to 298K. An anomalous variation of the graphitic c-axis which involves firstly negative-thermal-expansion (from 12K to ~50K), a saturation-effect (from 50K to ~160K) and then a positive expansion (from ~180K to 298K) is evidenced. The reported trend is significantly different with respect to that expected by considering the standard-thermal-expansion α-parameter where no saturation-effect is present. SQUID-magnetometry revealed further presence of superconducting-like hysteresis which resemble those observed by Scheike et al.

Item Type: Article
DOI/Identification number: 10.1088/2053-1591/ab6890
Divisions: Faculties > Sciences > School of Physical Sciences
Depositing User: Anna Corrias
Date Deposited: 09 Jan 2020 13:36 UTC
Last Modified: 09 Jan 2020 13:36 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/79522 (The current URI for this page, for reference purposes)
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