Surface magnetism of a semi-infinite decorated Ising system

Magnetic properties of the surface in a semi-infinite decorated Ising syste m with a random field at a decorated site are investigated by the effective -field theory. In particular, the phase diagram and magnetization curves fo r the bulk and surface of the simple cubic ferromagnetic (or ferrimagnetic) system with a (001) surface are examined numerically. We find a lot of cha racteristic features in them, such as the reentrant phenomenon, the possibi lity of two compensation points on the surface and unexpected magnetization curves at or near the surface associated with it. (C) 2000 Elsevier Scienc e B.V. All rights reserved.