Slow relaxation process in Ising-like Heisenberg kagome antiferromagnets due to macroscopic degeneracy in the ordered state

We study relaxation phenomena in the ferromagnetically ordered state of the Ising-like Heisenberg kagome antiferromagnets. We introduce the weathervane loop in order to characterize macroscopic degenerate ordered states and study the microscopic mechanism of the slow relaxation from a viewpoint of the dynamics of the weathervane loop configuration. This mechanism may give a possible origin of the slow relaxation reported in recent experiments.