Effect of magnetic fields on magnetic phase separation in anion-deficient manganite La0.70Sr0.30MnO2.85

The temperature dependence of the specific magnetic moment of anion-deficient manganite La0.70Sr0.30MnO2.85 is measured in external magnetic fields of 0-140 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 T-f=65-6H(0.21), while the temperature at which the ZFC- and FC-curves diverge varies at T-rev=250-90H(0.11). The cause of and mechanism for the magnetic phase separation are discussed. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3614412]