Collective charge response in the weak ferromagnetic phase of κ-(BEDT-TTF)2Cu[N(CN)2]Cl

We summarize the main features of the low frequency dielectric relaxation observed below 30K in the weak ferromagnetic state of κ-(BEDT-TTF)2Cu[N(CN)2]Cl. The observed width of the relaxation process is somewhat broader than for a Debye process and has a moderate strength of about 3.103. The mean relaxation time, which is much larger than expected for single particle excitations, is thermally activated in a manner similar to the dc conductivity and saturates below the antiferromagnetic phase transition. A charged domain wall in a random ferromagnetic domain structure is proposed as the relaxation entity.