Control of magnetism of magnetic thin films and nanowires by surface chemical modification studied by the surface magnetization-induced second harmonic generation technique

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Magnetic properties of metal thin films, wires and clusters have attracted much interest in recent years. This project aimed the control of the magnetic properties by means of surface chemical techniques such as adsorption and deposition of atoms and molecules on the metal thin films. As a new powerful measurement equipment, we have prepared the system of the etization induced second harmonic generation (MSHG) method and tried to apply this technique to some interesting magnetic systems. This technique is known to be very surface sensitive and is one of the most suitable methods for the present purposes. As the other measurement techniques, we have employed the x-ray magnetic circular dichroism (XMCD) and the magneto-optical Kerr effect (MOKE).We have first investigated the Ag-coated Co/Cu(1 1 17) system, which inherently shows a magnetic easy axis along the step while the easy axis becomes the step perpendicular direction after Ag deposition. In order to understand the mechanism of the spin reorientation transition, we have measured the magnetization curves using the MSHG and have found unique curves that could not be obtained by the MOKE. By combining the XMCD and MOKE results, we have discussed the microscopic mechanism of the spin transition.We have subsequently examined the Fe films on Ni/Cu(OO1). The previous study indicated that this system shows an exchange bias, this leading to the possibility of perpendicular exchange interaction. If this is true, this is the first thin film system with perpendicular exchange interaction within single magnetic phase systems. Actually, we have found beautiful magnetization curves along the direction perpendicular to the magnetic field. This system is further being investigated by means of MOKE and XMCD.