Magnetic circular dichroism studies with soft x-rays

Soft-x-ray magnetic circular dichroism (SXMCD) is a powerful tool to study the element and site specific magnetic moments in multi-component systems. This is demonstrated for a thin metal film overlayer system and a rare-earth/transition-metal compound. The magnetic properties of ultrathin Ni films on a Cu(100) substrate are investigated at the Ni L2,3 absorption edges. Temperature dependent SXMCD data of various film thickness yield Curie temperatures and the critical exponents used in scaling theories which describe two dimensional magnetic phase transitions. The magnetic moments of Gd and Fe in gadolinium iron garnet (Gd3Fe5O12) were probed at 77 K and 300 K at the Gd M4,5 and at the Fe L2,3 absorption edges. The SXMCD signal at each edge allows the magnetic ordering for each specific ion to be independently determined, and the temperature dependence confirms that the reversal of the macroscopic magnetization is due to the reversal of each local magnetic moment of the Fe and the Gd atoms when the compensation point (Tcomp = 288 K) is crossed.