Sharif Digital Repository

Ising model in nano systems are studied, in the presence of a magnetic field. For a one-dimensional(1-D) array of spins interacting via nearest-neighbor and next-nearest-neighbor interactions we calculated the heat capacity , the surface energy, the finite-size free energy, and bulk free energy per site. The heat capacity versus temperature exhibited a common wide peak for systems of any size. A small peak also appears at lower temperatures for small arrays when the ratio of magnetic field- spin interaction energy over the nearest-neighbour spin-spin interaction energy f is within and size. The peak becomes smaller for longer array and eventually vanishes for long arrays, disappearing when...