Influence of magnetic field on magnetic phase separation in anion-deficit manganite La070Sr0.30MnO2.85

The temperature dependence of the specific magnetic moment of anion-deficient manganite La070Sr0.30MnO2.85 is measured in external magnetic fields of 0 to140 kOe, with the prehistory taken into account. The inhomogeneous magnetic state is a cluster spin glass and is the result of a redistribution of oxygen vacancies. Increasing the external magnetic field initially (H<<10 kOe) leads to breakup of the ferromagnetic clusters, and then (H>=10 kOe) to a transition of the antiferromagnetic matrix into a ferromagnetic state and an increase in the degree of polarization of the local manganese spins. The freezing temperature for the magnetic moments varies as Tf=65-6H0.21, while the temperature at which the ZFC- and FC-curves diverge varies at Trev = 250-90H0.11. The reason and the mechanism of the magnetic phase separation are discussed.