125 resultados para abdominal wall musculature


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The periodicity of 180 degrees. stripe domains as a function of crystal thickness scales with the width of the domain walls, both for ferroelectric and for ferromagnetic materials. Here we derive an analytical expression for the generalized ferroic scaling factor and use this to calculate the domain wall thickness and gradient coefficients ( exchange constants) in some ferroelectric and ferromagnetic materials. We then use these to discuss some of the wider implications for the physics of ferroelectric nanodevices and periodically poled photonic crystals.

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Extremely regular self-organized patterns of 90o ferroelastic domains have been reported in freestanding single crystal thin films of ferroelectric BaTiO3. Lukyanchuk et al. [Phys Rev B 79, 144111 (2009)] have recently shown that the domain size as a function of thickness for such free standing films can be well described assuming that the domains are due to stress caused by a surface tension layer that does not undergo the paraelectric–ferroelectric transition. From the starting point of Lukyanchuk’s model, it is shown here that the ‘‘universal’’relationship between domain size and domain wall thickness previously observed in ferroelectrics, ferromagnets and multiferroics is also valid for ferroelastic domains.Further analysis of experimental data also shows that the domain wall thickness can vary considerably (an order of magnitude) from sample to sample even for the same material (BaTiO3), in spite of which the domain size scaling model is still valid, provided that the correct,sample dependent, domain wall thickness is used.