High Resolution X-Ray Scattering Study of the Anion Ordering Phase Transition of (TMTSF)₂ClO₄

抄録

The anions of (TMTSF)₂ClO₄ order below about 24 K. The speed at which this transition is passed has a drastic influence on the low temperature electronic properties of this salt. We determined as a function of the cooling rate the number of ordered ClO₄ as well as the average size of the ordered domains. A high resolution X-ray synchrotron radiation study showed that this transition exhibited very unusual features probably due to the coupling of the anions with angular deformations of the Bravais lattice during the ordering process. We investigated also the kinetics of the Ising order parameter describing the anion ordering by a study of the temporal evolution of a superlattice reflection during thermal annealing of quenched samples.