A comparative study on phase co-existence of La_(1/4)Pr_(3/8)Ca_(3/8)MnO_3 in a polycrystalline bulk and thin film

摘要

We present a comparative study on phase co-existence in La(1/4)Pr_(3/8)Ca_(3/8)MnO_3 (LPCMO) in a polycrystalline bulk and thin film form. The X-ray diffraction results confirm the formation of single-phase polycrystalline bulk and c-axis-oriented strained epitaxial thin films on a LaAlO_3 substrate. Scanning electron microscopy images show a homogeneous microstructure growth for both the bulk as well as thin film samples. The temperature dependent magnetization curves for bulk and thin film show remarkably different features indicating the presence of very different phase separation scenarios. A two-step rise and a large thermal hysteresis are observed between zero-field cooled and field-cooled magnetization plots in the bulk sample. However, the magnetization of the film shows a very small hysteresis and a negligible signature of the CO-AFM state for the same composition. The field dependent magnetization plots indicate that in a bulk form LPCMO is a soft magnet and shows a metamagnetic behaviour while in a thin film form it acts as a hard magnet and the metamagnetic behaviour is completely lost.