Magnetization Process of a Dilute Ising-Like Chain

Magnetization process at zero temperature is studied numerically for an Ising-like magnetic chain diluted with nonmagnetic impurities, which break up a magnetic chain into independent segments with various lengths. Calculations are made of the weighted contributions to the magnetization from each segment. The magnetization curve thus obtained shows successive metamagnetic transitions at lower fields in addition to the metamagnetic transition corresponding to the one in the pure case. These successive transitions are attributed to the instabilities of a single domain wall excitation including end-spin reversal process in various segments consisting of even numbers of spins. The characteristic features of the magnetization curve are consistent with recent experimental results on CsCoMgC at very low temperatures.