  We study ferrimagnetism in the ground state of the antiferromagnetic
Heisenberg model on the spatially anisotropic kagome lattice, in which
ferrimagnetism of the conventional Lieb-Mattis type appears in the region of
weak frustration whereas the ground state is nonmagnetic in the isotropic case.
Numerical diagonalizations of small finite-size clusters are carried out to
examine the spontaneous magnetization. We find that the spontaneous
magnetization changes continuously in the intermediate region between
conventional ferrimagnetism and the nonmagnetic phase. Local magnetization of
the intermediate state shows strong dependence on the site position, which
suggests non-Lieb-Mattis ferrimagnetism.
