Magnetic properties, Lyapunov exponent and superstability of the spin- Ising–Heisenberg model on a diamond chain

The exactly solvable spin- 1 2 Ising–Heisenberg model on a diamond chain has been considered. We have found the exact results for the magnetization using the recursion relation method. The existence of the magnetization plateau has been observed at one third of the saturation magnetization in the antiferromagnetic case. Some ground-state properties of the model are examined. At low temperatures, the system has two ferrimagnetic (FRI1 and FRI2) phases and one paramagnetic (PRM) phase. Lyapunov exponents for the various values of the exchange parameters and temperatures have been analyzed. It has also been shown that the maximal Lyapunov exponent exhibits plateau. Lyapunov exponents exhibit different behavior for two ferrimagnetic phases. We have found the existence of the supercritical point for the multi-dimensional rational mapping of the spin- 1 2 Ising–Heisenberg model on a diamond chain for the first time in the absence of the external magnetic field and T → 0 in the antiferromagnetic case.