Field Induced ferromagnetic fraction enlargement in phase separated La0.5Ca0.5MnO3

L. GHIVELDER; R. S. FREITAS; JOAQUIN SACANELL; F. PARISI; P. LEVY

Seattle, USA

Conferencia; March Meeting; 2001

American Physical Society

A systematic study of the magnetic and transport properties of a series of phase separated La_0.5Ca_0.5MnO_3 compounds is reported. The investigated samples all have the same composition but different grain sizes, which modifies the volume fraction of the coexisting ferromagnetic (FM) and antiferromagnetic charge-ordered (AFM-CO) phases. Magnetoresistance and magnetization measurements were performed with two different experimental procedures: a standard field-cooled cooling (FC) mode, and a second method in which the field is turned on only while measuring each data point, and switched off while cooling the samples. Magnetization and magnetoresistance measurements display big differences when comparing the data obtained with the different procedures. The overall results are interpret in terms of a field induced FM fraction enlargement. In transport measurements this effect yield a percolative transition. Magnetization data shows evidence for the formation of AFM-CO regions within the FM phase.