Low-temperature thermodynamics of the asymmetric next-nearest-neighbor Ising model

Low-temperature thermodynamics of the asymmetric next-nearest-neighbor Isin g (ASYNNNI) model is analyzed. It is demonstrated that this model at low te mperatures is equivalent to one-dimensional (1D) NN Ising model in zero ext ernal held with the NN interaction being a copper mediated NNN interaction of the ASYNNNI model, V-2<0. It is also shown that the spin correlation fun ction xi v(2)(r) = (sigma(i)sigma(i+r)) - (sigma(i))(2) along Cu-O(1) chain s decays exponentially with interspin distance r at T approximate to 0.