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Magnetic force microscope (MFM) tips are prepared by coating silicon tips of 4 nm radius with 20-nm-thick metallic magnetic films with and without 2-nm-thick oxidation protection layers. Iron (Fe) is used as the magnetic material, whereas carbon (C), silicon nitride (Si-N), or silicon carbide (Si-C) is employed as the protection layer. The MFM tips are exposed in an environment of high temperature of 70 °C and high relative humidity of nearly 100%. The effect of protection layer on the spatial resolution is investigated as a function of period of exposure to the environment. The resolution of MFM tip without protection layer deteriorates from 7.2 to 21.2 nm in 10 days. The deterioration is attributed to an increase in the tip radius and a loss of the detection sensitivity caused by oxidation of coated Fe material. In contrast, the resolutions of tips with C, Si-N, and Si-C layers are kept almost constant at 12.1 ± 0.5, 12.1 ± 0.5, and 14.8 ± 2.1 nm for a time span of 10 days, respectively. The coating of a very thin protection layer has been shown effective in keeping the MFM tip performance for a long period of time by preventing the oxidation of coated metallic magnetic material.

Co thin films were prepared on Al2O3 single-crystal substrates with (0001) and (11-20) orientations by ultra-high vacuum molecular beam epitaxy. Effects of substrate temperature and substrate orientation on the film structure were investigated. Co epitaxial thin films with close-packed planes parallel to the substrate surfaces are obtained on Al2O3(0001) and Al2O3(11-20) substrates at 50-500 °C and 300-500 °C, respectively. The films grown on Al2O3(0001) substrates at temperatures lower than 100 °C consist of fcc-Co(111) crystal. With increasing the substrate temperature, hcp-Co(0001) crystal begins to coexist with the fcc crystal and the volume ratio of hcp to fcc crystal increases. The films grown at temperatures higher than 300 °C consist primarily of hcp crystal coexisting with a small volume of fcc crystal. On the contrary, the Co thin films grown on Al2O3(11-20) substrates at temperatures higher than 300 °C consist of only the hcp crystal. The in-plane lattice strains of these Co epitaxial films are larger than the out-of-plane lattice strains due to the accommodation of lattice mismatches between the films and the substrates. The film strain decreases as the substrate temperature increases.

FeCo thin films were prepared on SrTiO3(100), SrTiO3(110), and SrTiO3(111) single-crystal substrates by ultra-high vacuum molecular beam epitaxy. The film growth structure and magnetic properties were investigated. FeCo epitaxial thin films are obtained on these SrTiO3 substrates at elevated temperatures with different crystal growth orientations. The nucleation and growth process of FeCo thin films on SrTiO3 substrates vary depending on the orientation of the substrate and its temperature. FeCo(100) single-crystal thin films with an A2 structure are obtained on SrTiO3(100) substrates at 500°C. FeCo epitaxial thin films with (110)A2 and (211)A2 planes parallel to the substrate surface are obtained on SrTiO3(110) substrates. FeCo thin films epitaxially grown on SrTiO3(111) substrates consist of two crystallographic phases having A2 and hexagonal structures with the (110)A2 and (0001)hex planes parallel to the substrate surface. The metastable FeCo(0001)hex plane is presumably formed in order to relax the strain caused by the lattice mismatch at the FeCo/SrTiO3(111) interface. The lattice constants of Fe50Co50 crystal with the hexagonal structure are estimated to be a = 0.251±0.004 nm and c = 0.457±0.005 nm. The magnetic properties of FeCo epitaxial thin films grown on SrTiO3 substrates are influenced by the magnetocrystalline anisotropy and shape anisotropy caused by the roughness of FeCo islands that form the FeCo thin films.

Ni thin films were prepared on MgO(100), MgO(110), and MgO(111) single-crystal substrates in the temperature range between 100 and 500°C by UHV-MBE. The growth process, surface morphology, and magnetic properties were investigated. Ni epitaxial thin films were obtained with different film growth orientations depending on the substrate crystal. When Ni films were deposited on MgO(100) substrates, RHEED reflection from hcp-Ni(1120) crystal was observed. However, X-ray diffraction analysis of the samples indicates that the resulting film structure is fcc-Ni(100), suggesting that the hcp-Ni(1120) is metastable and that most of the film has been transformed into a more stable fcc structure. In contrast, Ni epitaxial thin films with (110)fcc and (111)fcc planes parallel to the substrate surface were obtained on MgO(110) and MgO(111) substrates, respectively. The lattice spacings were almost in agreement with the bulk fcc-Ni values for the Ni films prepared on these MgO substrates. The surface morphology influences the magnetic properties of Ni films grown on MgO substrates.

Ni epitaxial thin films were prepared on Au(100)fcc underlayers hetero-epitaxially grown on MgO(100)B1 single-crystal substrates by ultra-high vacuum molecular beam epitaxy. The effects of substrate temperature on the structural and the magnetic properties were investigated. hcp-Ni crystals are successfully obtained at temperatures lower than 300°C. With increasing the substrate temperature, the volume ratio of more stable fcc phase increases in the film. The hcp-Ni crystal consists of two types of (11-20) domains whose c-axes are rotated around the film normal by 90°each other. X-ray diffraction shows that the Ni film prepared at 100°C consists primarily of hcp crystal. An atomically sharp boundary is recognized at the Ni(11-20)hcp/Au(100)fcc interface for the Ni film. The in-plane magnetization properties of hcp-Ni film are interpreted to be reflecting the magnetocrystalline anisotropy of bulk hcp-Ni crystal which was predicted by a computer simulation study.

FeCo thin films were prepared on MgO(100), MgO(110), and MgO(111) single-crystal substrates by UHV-MBE. The effects of substrate orientation and substrate temperature on the film growth structure and the magnetic properties were investigated. FeCo thin films with (100)bcc, (211)bcc, and (110)bcc planes parallel to the substrate surface grew epitaxially on respective MgO substrates. FeCo(100)bcc single-crystal films were obtained on MgO(100) substrates. FeCo(211)bcc bi-crystalline films grew epitaxially on MgO(110) substrates with two types of domains whose orientations were rotated around the film normal by 180 degrees with respect to each other. FeCo(110)bcc thin films grew epitaxially on MgO(111) substrates with two type variants namely, the Nishiyama-Wasserman and Kurdjumov-Sachs relationships. Atomically sharp boundaries were recognized between the FeCo thin films and the MgO substrates, where misfit dislocations were introduced in the FeCo thin films, presumably to decrease the lattice misfits. A 0.3% reduction of the lattice spacing normal to the substrate surface was observed for an FeCo thin film prepared at a substrate temperature of 100 °C. The lattice spacing reduction decreased with increasing substrate temperature. The magnetic properties of FeCo thin films grown on MgO substrates were influenced by the magnetocrystalline anisotropy and the shape anisotropy caused by the roughness of FeCo islands which form the FeCo thin films.