Chirality mechanism of spin-glass ordering

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Spin glass has been studied quite extensively as a typical example of 'complex' systems where the effects of frustration and randomness coexist. The present project has been performed with the aim of testing the validity of the chirality mechanism of the experimental spin-glass ordering proposed recently to explain some of the puzzles of the experiments. Via large-scale simulations on isotropic as well as weakly anisotropic three-dimensional Heisenberg spin-glass models in zero field, we have confirmed the occurrence of the chiral-glass transition at a finite temperature without the standard spin-glass order. In real spin glasses, weak but finite random magnetic anisotropy inevitably exits and is expected to play an important role in the spin-glass ordering. We have also performed large-scale simulations on the weakly anisotropic systems and have obtained the results supporting the occurrence of the spin-chirality recoupling predicted by the chirality mechanism. We have also performed large-scale simulations for the three-dimensional Heisenberg spin glass in magnetic fields, and found that the chiral-glass transition of the same kind as in zero field occurs, the shape of the associated transition line being regular in the zero-field limit. Again, the results are consistent with the prediction of the chirality mechanism.