Domain-Wall dynamics in the disordered ferromagnet LaMnO3.075

Low-field ac susceptibility measurements have been made on the cation-deficient perovskite manganite LaMnO3.075. As the temperature is increased toward T-C (122 K), the real part of the ac susceptibility (chi') exhibits discontinuous jumps at roughly regular intervals, followed by gradual decays on the high-temperature side, resulting in a series of spikes in the chi' vs temperature plot. It is argued that the spikes appear as a consequence of disaccommodation, combined with periodic, spontaneous domain-wall jumps.