Phase separation and low-field bulk magnetic properties of Pr_0.7Ca_0.3MnO₃

We present a detailed magnetic study of the perovskite manganite Pr_0.7Ca_0.3MnO₃ at low temperatures including magnetization and ac susceptibility measurements. The data appear to exclude a conventional spin glass phase at low fields, suggesting instead the presence of correlated ferromagnetic clusters embedded in a charge-ordered matrix. We examine the growth of the ferromagnetic clusters with increasing magnetic field as they expand to occupy almost the entire sample at H∼0.5 T. Since this is well below the field required to induce a metallic state, our results point to the existence of a field-induced ferromagnetic insulating state in this material.