Finite-size-scaling analyses of the chiral ordert in the Josephson-junction ladder with half a flux quantum per plaquette |
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Authors: | Yoshihiro Nishiyama |
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Institution: | (1) Department of Physics, Faculty of Science, Okayama University, Okayama 700-8530, Japan, JP |
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Abstract: | Chiral order of the Josephson-junction ladder with half a flux quantum per plaquette is studied by means of the exact diagonalization
method. We consider an extreme quantum limit where each superconductor grain (order parameter) is represented by S=1/2 spin. So far, the semi-classical case, where each spin reduces to a plane rotator, has been considered extensively. We found that in the case of S=1/2, owing to the strong quantum fluctuations, the chiral (vortex lattice) order becomes dissolved except in a region, where
attractive intrachain and, to our surprise, repulsive interchain interactions both exist. On the contrary, for considerably
wide range of parameters, the superconductor (XY) order is kept critical. The present results are regarded as a demonstration of the critical phase accompanying chiral-symmetry
breaking predicted for frustrated XXZ chain field-theoretically.
Received 20 February 2000 |
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Keywords: | PACS 75 10 Jm Quantized spin models - 85 25 Cp Josephson devices - 75 40 Mg Numerical simulation studies |
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