NANO-ORDERED PALPUS-LIKE CRYSTALS IN La1/3Ca2/3MnO3 FILMS

The surface of La1/3Ca2/3MnO3 (LCMO) films with thickness, t, ranging from 4 to 150 nm has been studied. Highly ordered palpus-like crystals induced by strain are observed in the films grown on the substrate of SrTiO3 (with thickness t ranging from 20 to 50 nm) and on sapphire (with thickness t ranging from 30 to 50 nm). The strain is identified to result from thermal expansion mismatch between the substrate and the film, and thermal expansion anomaly may exist at a high temperature induced by possible phase transition in LCMO with t = 30 nm. Such a phenomenon may arrest the film growth and the understanding of colossal magnetoresistance materials as well as provide a new way to make ordered structures for applications.