Spin-resonance experiments allowed us to study the kinetics of ordering in the quasi-two-dimensional order-disorder phase transition observed at $T_c$=210±2 K in stage-4 ${\mathrm{SbCl}}_5$-intercalated graphite. Quenching from the disordered phase (T≫$T_c$) reveals a time broadening of the linewidth with a scaling behavior (∼$t^n$), which we attribute to the time growth of the average linear domain size of a weakly incommensurate superlattice. Fittings of the experimental data give n≃0.48 for T<$T_c$ and n≃0.55 for T>$T_c$, which are close to the exponents obtained in Monte Carlo simulations for domain growth of degenerate superlattices. For T≃$T_c$ a much faster kinetics is observed, which may indicate the presence of critical phenomena. A more sluggish kinetics is observed after an elapsed time of approximately 50 min, and at low temperatures (T≪$T_c$), the results indicate that the system is in a metastable frozen-in state.

• Received 22 September 1986

DOI:https://doi.org/10.1103/PhysRevB.36.2893