Unusual magnetic properties in nanosized La_(0.4)Ca _(0.6)MnO_3

摘要

The magnetic properties of nanosized La_(0.4)Ca _(0.6)MnO_3 samples with different particle size were investigated. Reducing the particle size can significantly suppress antiferromagnetism and charge ordering. Unlike other charge ordering manganites, in which the exchange bias (EB) field shows a maximum for a certain particle size, the EB field shows a minimum value at ～180 nm in the present samples. The size-dependent EB can be understood in terms of the antiferromagnetic (AFM) domain state model in small particles and the decrease of the volume of ferromagnetic (FM) component in large particles.