A Geometrical Model for Stagnant Motion in Hamiltonian Systems with Many Degrees of Freedom

We introduce a model of Poincar\'e mappings which represents hierarchical structure of phase spaces for systems with many degrees of freedom. The model yields residence time distribution of power type, hence temporal correlation remains long. The power law behavior is enhanced as the system size increases.Comment: 6 pages, 3 Encapsulated Postscript figures, LaTeX (58 kb

Effect of strain on the electrical transport and magnetization of the epitaxial Pr0.5Ca0.5MnO3/La0.5Ca0.5MnO3/ Pr0.5Ca0.5MnO3 trilayer structures

Epitaxial trilayer structures consisting of two antifferomagnetic charge/orbital order insulators Pr0.5Ca0.5MnO3 (PCMO) and La0.5Ca0.5MnO3 (LCMO) are grown on (001)-oriented SrTiO3 and LaAlO3 substrates. In this trilayer series, a thin film of LCMO with various thicknesses is sandwiched between the two fixed thicknesses of PCMO. These samples show a Curie temperature with a hysteretic field dependent magnetization at 10 K, although the individual compounds are antiferromagnetic. The zero field electronic transport of all samples on LAO shows thermally activated behavior, while the thermally activated behavior is suppressed and a metal-like transport is appearing for the samples on STO as the LCMO layer thickness increases above 10 unit cell. We have discussed these magnetic and transport properties of the trilayer structures on STO and LAO by the interfacial effect due to the stabilized CO state and the vibration mode of Jahn-Teller distortion.Comment: To be pubslised in Phys. Rev.