Novel magnetization and susceptibility originated in the nanomagnet of disordered nickelates

We have applied the mean field theory to calculate the magnetization and susceptibility contributed by the spin distribution in a nanomagnet which is a common unit in nickelate superconductors and several related compounds. Spin distribution of NiO $$_6$$ has been considered as a basic unit of which spins interact with each other via disordered exchange integral. Spins in apex positions and planar positions are separated by a variable distance which has been modeled. By using the mean field approach the magnetization and susceptibility have been calculated as a function of (i) magnetic field, (ii) temperature and (iii) interspin separation. Effects of the apex spin disorder at several extreme conditions have been quantified and found to be very strong on magnetic moments and susceptibility.