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Full-Text Articles in Physical Sciences and Mathematics
N-Color Spin Models In The Large N Limit, Mehran Kardar, Miron Kaufman
N-Color Spin Models In The Large N Limit, Mehran Kardar, Miron Kaufman
Miron Kaufman
N color spin models are introduced and examined in the large N limit. The free energy and critical properties at the phase transition are studied. With relevant couplings between colors the transition becomes either first order or Fisher renormalized. With irrelevant couplings there is a crossover to first-order transitions through a nonclassical tricritical point. Connections are established between the N-color model, compressible systems, and systems with random impurities.
Random-Field Critical Behavior And The Ginzburg Criterion, Miron Kaufman, Mehran Kardar
Random-Field Critical Behavior And The Ginzburg Criterion, Miron Kaufman, Mehran Kardar
Miron Kaufman
The Ginzburg criterion for crossover from classical to nonclassical critical behavior is derived in the presence of random fields. Experiments on dilute antiferromagnets in a field are examined, and the possibility of such a crossover is investigated. We also point out that the (necessarily) symmetric logarithmic divergence observed in birefringence measurements can be accompanied by a discontinuity, and a fitting form which allows for this and other corrections to scaling is proposed.