Re-entrant spin glass transition in La0.96-yNdyK0.04MnO3: Origin and effects on the colossal magnetoresistivity

摘要

Magnetic, electric and structural properties of La0.96-yNdyK0.04MnO3+delta with 0 less than or equal to y less than or equal to 0.4 have been studied experimentally. A disordered magnetic state is formed as La is substituted by Nd, reflecting the competition between ferromagnetic (FM) double exchange and antiferromagnetic superexchange interactions. Key structural parameters are identified and correlated with changes in magnetic and electric properties. By application of a large magnetic field, spin disorder scattering is removed, creating a new magnetoresistance peak at a temperature lower than the first near-T-c, peak. Time-dependent zero-field-cooled magnetisation measurements have been performed for y = 0.4 around this temperature. A re-entrant spin glass (RSG) transition is evidenced, with low field ageing properties in both the RSG and FM phases, similar to those observed in archetypal spin glass materials. [References: 22]