Shape dependences of magnetic properties in 2D Ising nano-particles

The shape dependences of magnetic properties (phase diagram and magnetization) in two (circle and square) 2D Ising nano-particles are investigated by the use of both the core-shell model and the effective field theory with correlations, in order to clarify the effects of the shape difference to them. Particular emphasis is given to the effect to the magnetizations when the core-shell exchange coupling takes a different (positive or negative) sing. Some common phenomena are also found in the magnetic properties between the two nanosystems.