Tilted and Crossing Vortex Chains in Layered Superconductors |
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Authors: | A E Koshelev |
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Affiliation: | (1) Materials Science Division, Argonne National Laboratory, Argonne, Illinois, 60439 |
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Abstract: | No Heading In presence of the Josephson vortex lattice in layered superconductors, small c-axis magnetic field penetrates in the form of vortex chains. In general, structure of a single chain is determined by the ratio of the London ] and Josephson J] lengths, = / J. The chain is composed of tilted vortices at large ![agr](/content/k7752681l70h1266/xxlarge945.gif) s (tilted chain) and at small ![agr](/content/k7752681l70h1266/xxlarge945.gif) s it consists of crossing array of Josephson vortices and pancake-vortex stacks (crossing chain). We study chain structures at the intermediate ![agr](/content/k7752681l70h1266/xxlarge945.gif) s and found two types of phase transitions. For 0.6 the ground state is given by the crossing chain in a wide range of pancake separations a 2–3] J. However, due to attractive coupling between deformed pancake stacks, the equilibrium separation can not exceed some maximum value depending on the in-plane field and . The first phase transition takes place with decreasing pancake-stack separation a at a = 1 – 2] J, and rather wide range of the ratio , 0.4 0.65. With decreasing a, the crossing chain goes through intermediate strongly-deformed configurations and smoothly transforms into the tilted chain via the second-order phase transition. Another phase transition occurs at very small densities of pancake vortices, a 20 – 30] J, and only when exceeds a certain critical value 0.5. In this case small c-axis field penetrates in the form of kinks. However, at very small concentration of kinks, the kinked chains are replaced with strongly deformed crossing chains via the first-order phase transition. This transition is accompanied by a very large jump in the pancake density.PACS numbers: 74.25.Qt, 74.25.Op, 74.20.De |
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