Structural and Magnetic Properties of Dy/Cr Multilayers and Bilayers Grown by Molecular-Beam Deposition

Abstract

We studied the structural, magnetic and magnetotransport properties of the Dy/Cr multilayers and bilayers grown by molecular-beam deposition. Structures were analyzed by reflection high-energy electron diffraction and X-ray diffraction. The field and temperature dependences of magnetization and magnetoresistance were measured. We found that the Dy and Cr layers in the first bilayers take particular orientational relationships. However, in the subsequent bilayers, thin Cr layers are amorphous/fine crystalline whereas thick Cr layers are polycrystalline, and 2.5-nm-thick Dy layers are polycrystalline. The easy magnetization axis lies in the in-pane direction in most cases. Magnetization curves do not significantly depend on the Cr layer thickness of the multilayers, and there is no evidence of the interlayer exchange coupling of Dy through Cr layers. This may be ascribed to an amorphous Cr layer with a small thickness. Magnetization–temperature (M–T) curves differ depending on cooling conditions. Peaks appear in the M–T curves during the temperature-increase of demagnetized multilayers at a magnetic field. The causes for these phenomena were discussed.