Regensburg 2002 – wissenschaftliches Programm
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DF: Dielektrische Festkörper
DF 6: Poster
DF 6.9: Poster
Mittwoch, 13. März 2002, 14:30–18:00, Poster Chemie C
35Cl NMR and 35Cl NQR studies of the incommensurately modulated crystal of bis(4-chlorophenyl)sulfone (BCPS) — •Dieter Michel1, Abdoulaye Taye1, Frank Decker2 und Jörn Petersson2 — 1University of Leipzig, Faculty of Physics and Geosciences, D-04103 Leipzig — 2University of the Saarland, Department of Physics,D-66041 Saarbrücken
BCPS undergoes a transition from a normal N phase with a monoclinic I2/a structure into an one dimensionally modulated IC phase at a temperature Ti of about 150 K. Because the IC phase was found to exist down to 0 K, studies on this crystal are of particular interest. The incommensurate modulation wave can be represented by an order parameter (OP) with two thermodynamic degrees of freedom, e.g. amplitude and initial phase. 35Cl quadrupolar perturbed nuclear magnetic resonance (NMR) and 35Cl nuclear quadrupole resonance (NQR) methods are applied independently of each other to investigate the critical order parameter fluctuations by means NMR and NQR spin-lattice relaxation time T1 measurements. Closely above Ti considerable critical contributions to 1/T1 are detected showing critical exponents of 0.66±0.03. These values excellently fit to similar critical exponents for 1/T1 derived also for other IC modulated crystals [1]. The exponents obey the known scaling laws and point to universal properties which can be described on the basis of the 3D-XY model. Supported by the DFG. [1] Decker, F. et al., 2001 Phys. Rev. B 64, in press