Eur. Phys. J. B 8, 507-510 (1999)
https://doi.org/10.1007/s100510050718

Pseudocritical NMR frequency shift above the normal-incommensurate phase transition

Fachbereich Physik, Universität des Saarlandes, Postfach 151150, 66041 Saarbrücken, Germany

Received: 6 August 1998
Published online: 15 April 1999

Abstract

The NMR satellite frequencies were measured as a function of temperature in the normal high-temperature phase for ⁸⁷Rb in Rb₂ZnBr₄ and Rb₂ZnCl₄ and for ³⁵Cl in betaine calciumchloride dihydrate. Approaching the respective normal-incommensurate phase transition an anomalous shift of the NMR frequency is observed for the first two cases. This effect is ascribed to the increasing order parameter fluctuations. The experimental data are compared to calculations which relate the observed behaviour of the NMR frequencies to the non-classical critical behaviour of the substances under investigation.