Determining ethylene group disorder levels in {kappa}-(BEDT-TTF){sub 2}Cu[N(China){sub 2}]Br

We present a detailed structural investigation of the organic superconductor {kappa}-(BEDT-TTF){sub 2}Cu[N(China){sub 2}]Br at temperatures T from 9 to 300 K. Anomalies in the T dependence of the lattice parameters are associated with a glasslike transition previously reported at T{sub g}=77 K. From...

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Bibliographic Details
Published in:Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2007-03, Vol.75 (10)
Main Authors: Wolter, A. U. B., Hahn-Meitner-Institut GmbH, c/o BESSY, 12489 Berlin, Feyerherm, R., Dudzik, E., Suellow, S., Strack, Ch, Lang, M., Schweitzer, D.
Format: Article
Language:English
Subjects:
BEDT-TTF
CARBON NITRIDES
CRYSTALS
CYANIDES
ETHYLENE
FREEZING OUT
GLASS
LATTICE PARAMETERS
MATERIALS SCIENCE
ORTHORHOMBIC LATTICES
SPACE GROUPS
SYMMETRY
TEMPERATURE DEPENDENCE
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Summary:We present a detailed structural investigation of the organic superconductor {kappa}-(BEDT-TTF){sub 2}Cu[N(China){sub 2}]Br at temperatures T from 9 to 300 K. Anomalies in the T dependence of the lattice parameters are associated with a glasslike transition previously reported at T{sub g}=77 K. From structure refinements at 9, 100, and 300 K, the orthorhombic crystalline symmetry, space group Pnma, is established at all temperatures. Further, we extract the T dependence of the occupation factor of the eclipsed conformation of the terminal ethylene groups of the BEDT-TTF molecule. At 300 K, we find 67(2)%, with an increase to 97(3)% at 9 K. We conclude that the glasslike transition is not primarily caused by configurational freezing-out of the ethylene groups.
ISSN:1098-0121
1550-235X
DOI:10.1103/PHYSREVB.75.104512