Spin Ordering in Low-Dimensional Magnetic System Induced by Model Interaction

The magnetic susceptibility has been studied by using a new trial function for the model interaction between spins arranged in a low-dimensional square pyramidal system. We suggest that the exchange interaction depends on a power exponent which depends on the pyramidal structure in addition to the magnetic energy and thermal energy. We have calculated the magnetization as a function of the temperature and magnetic field keeping the exponent constant. Dependence of the susceptibility on a characteristic length related to the low-dimensional system exhibits novel features. Magnetic field dependence of the susceptibility has a maximum which shifts toward higher field as the temperature is increased. Even at higher fields, the susceptibility can be very small. The variations of the susceptibility with temperature exhibit maximum which depends on the external perturbing field.