Magnetic and film structures of NO, CO adsorbed Fe/Cu (001)

CO and NO adsorption effects on the magnetism of 2 and 4 ML Fe thin films on Cu(001) were studied. The changes of magnetic structures were discussed in a relationship to crystalline structures of the films. The magnetic structure of the Fe(2 ML)/Cu(001) film was not affected by CO adsorption, but CO adsorption on Fe(4 ML)/Cu(001) caused a spin reorientation transition to in plane. Moreover, the magnetization was apparently reduced to the half of the initial value. The reason of the apparent reduction of the magnetization was studied by means of a depth resolved XMCD technique. The surface two layers of the film lose the magnetization, and only the bottom two layers keep the magnetization. These films were examined by EXAFS measurements to reveal a structural difference between the magnetically live layers and magnetically dead layers. Also, a NO adsorbed Fe 4 ML film has the in-plane easy axes of magnetization, and the magnetization of the topmost layer aligns in the opposite direction to the other layers. The antiferromagnetism in the surface layers has been caused by NO adsorption on the Fe/Cu(001) film. (author)