The specific heat of the rwo-dimensional +/-J Ising model

H. Kitatani; T. Chino; H. Ohya

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arXiv · cond-mat/0212579

The specific heat of the rwo-dimensional +/-J Ising model

H. Kitatani·T. Chino·H. Ohya

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Abstract

The specific heat of the two-dimensional $\pm J$ Ising model has been investigated by the numerical transfer matrix method and Monte Carlo simulations from a new point of view. The region where a part of the specific heat takes the negative value has been investigated, which is characteristic of frustrated systems and reflects the non-trivial degeneracy of the ground state. The region mentioned above is found to be fairly large in the $p-T$ plane ($p$ is the concentration of the ferromagnetic bond and $T$ is the temperature). Moreover, it includes the Nishimori line. Namely, it includes a part of the paramagnetic-ferromagnetic phase boundary, on which the specific heat cannot diverge. The present result indicates that the specific heat does not diverge at least on a part of the paramagnetic-ferromagnetic phase boundary above the multicritical point, which is in conflict with previous results.

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H. Kitatani, T. Chino, H. Ohya. 2002-12-24. The specific heat of the rwo-dimensional +/-J Ising model. https://arxiv.org/abs/cond-mat/0212579

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