Observation of charge-ordered state in heterogeneous La0.7Ca0.3MnO3-d thin film with oxygen deficiency

• Published in: Physica status solidi. A, Applied research Vol. 196; no. 1; pp. 74 - 77
• Main Authors: Prokhorov, V G, Lee, Y P, Komashko, V A, Svetchnikov, V L, Park, J S
• Format: Journal Article
• Language: English
• Published: 01-03-2003
• ISSN: 0031-8965

The magnetic and transport investigations were carried out for oxygen-deficit La0.7Ca0.3MnO3-*d films (*d #~ 0.1) with different thicknesses d. The X-ray diffraction and high-resolution electron-microscopy data showed that growth in the film thickness leads to a structural transition from the lattice-strained cubic (the out-of-plane lattice parameter c #~ 0.379 nm) to the relaxed rhombohedral phase (c #~ 0.395 nm). The evidence for the charge-ordered insulating (COI) state was observed for the compressed cubic phase which is formed in the thin (d #~ 30 nm) film owing to the epitaxial growth. An applied magnetic field (5T) melts the COI state and leads to the transition to the ferromagnetic metal-like state. The magnetic data showed that the Curie point is shifted from #~100 K for the rhombohedral phase to #~230 K for the cubic one. It was claimed that the formation of COI state and the shift in Curie point are governed by the compression of crystal lattice rather than the accumulation of oxygen vacancies.