A phase transition at 168 K has been recognized from the thermal hysteresis of the conduction-carrier spin-resonance parameters in the stage-7 acceptor ${\mathrm{AlCl}}_3$-graphite intercalated compound (GIC). Below the transition temperature, the final low-temperature in-plane residual resistivity of the sample was found to be dependent on its previous thermal history. Paradoxically, quenching effects, contrary to previous reports on low-stage acceptor GIC’s, leave the system in an ‘‘orderedlike’’ state of higher in-plane conductivity.

• Received 17 May 1985

DOI:https://doi.org/10.1103/PhysRevB.32.4774