4,631 research outputs found

    Spin-glass phase transition and behavior of nonlinear susceptibility in the Sherrington-Kirkpatrick model with random fields

    Get PDF
    The behavior of the nonlinear susceptibility χ3\chi_3 and its relation to the spin-glass transition temperature TfT_f, in the presence of random fields, are investigated. To accomplish this task, the Sherrington-Kirkpatrick model is studied through the replica formalism, within a one-step replica-symmetry-breaking procedure. In addition, the dependence of the Almeida-Thouless eigenvalue λAT\lambda_{\rm AT} (replicon) on the random fields is analyzed. Particularly, in absence of random fields, the temperature TfT_f can be traced by a divergence in the spin-glass susceptibility χSG\chi_{\rm SG}, which presents a term inversely proportional to the replicon λAT\lambda_{\rm AT}. As a result of a relation between χSG\chi_{\rm SG} and χ3\chi_3, the latter also presents a divergence at TfT_f, which comes as a direct consequence of λAT=0\lambda_{\rm AT}=0 at TfT_f. However, our results show that, in the presence of random fields, χ3\chi_3 presents a rounded maximum at a temperature T∗T^{*}, which does not coincide with the spin-glass transition temperature TfT_f (i.e., T∗>TfT^* > T_f for a given applied random field). Thus, the maximum value of χ3\chi_3 at T∗T^* reflects the effects of the random fields in the paramagnetic phase, instead of the non-trivial ergodicity breaking associated with the spin-glass phase transition. It is also shown that χ3\chi_3 still maintains a dependence on the replicon λAT\lambda_{\rm AT}, although in a more complicated way, as compared with the case without random fields. These results are discussed in view of recent observations in the LiHox_xY1−x_{1-x}F4_4 compound.Comment: accepted for publication in PR

    Procedimento de operação, manutenção e verificação de thermomixer.

    Get PDF
    bitstream/CENARGEN/29576/1/ct060.pd

    Procedimento de operação, manutenção e verificação da centrífuga refrigerada de bancada Eppendorf, Modelo 5810 R.

    Get PDF
    bitstream/CENARGEN/29583/1/ct063.pd

    Procedimento de operação, manutenção e verificação da estufa ELETROLAB modelo 112FC.

    Get PDF
    bitstream/CENARGEN/29586/1/ct065.pd
    • …
    corecore