We studied the crystal growth and structures of hexagonal close-packed Dy layers grown on body-centered cubic (100) and (211)Cr thin films using molecular-beam epitaxy. The (100) and (211)Cr films with smooth surfaces were prepared by growing Cr on (100) and (110)MgO substrates, respectively. The Dy layers were grown on these Cr thin films. During growth, surface structures were monitored by reflection high-energy electron diffraction. After growth, X-ray diffractometry was performed to analyze film structures. We found that Dy layers grow epitaxially on (100)Cr at 50 °C with two types of predominant domain: Dy(0001)[2110] ∥ Cr(100)[001] and Dy(0001)[0110] ∥ Cr(100)[001]. We also found that (1012)Dy grows epitaxially at 50 °C on (211)Cr with a tilt of approximately 3.7°. The orientational relationship is tilted-Dy(1012)[1210] ∥ Cr(211)[111]. These orientational relationships were discussed in connection with crystal structures and geometrical relationships. We show that the observed orientational relationships can be successfully explained in terms of strain with the aid of geometrical consideration.

We studied the growth and structures of Dy/Cr multilayers on Cr buffer layers formed on MgO substrates using a molecular-beam epitaxy technique. Reflection high-energy electron diffraction and X-ray diffraction analyses reveal that the periodic structure can be formed for various combinations of Dy and Cr layer thicknesses. The first Dy layers grow epitaxially on the Cr buffer although they are not single crystals. However, the subsequent layers become amorphous or finely crystalline for smaller thicknesses and polycrystalline for larger ones. The causes for these results are briefly discussed.

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.

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