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Perpendicularly magnetized films exhibiting small saturation magnetizations ( M s ) are essential for spin-transfer-torque magnetoresistive random access memories (MRAMs). In this study, the intermetallic compound (Mn–Cr)AlGe with a Cu2Sb crystal structure was investigated as a material exhibiting low M s (∼ 300 kA/m) and high-perpendicular magnetic anisotropy energy ( K u ). The layer thickness dependence of K u and effects of Mg-insertion layers at the top and bottom (Mn–Cr)AlGe|MgO interfaces were studied for film samples fabricated onto thermally oxidized silicon substrates to realize high K u values in the thickness range of a few nanometers. The values of K u were approximately 7 × 10 5 and 2 × 10 5 J/m3 at room temperature for 5 and 3 nm-thick (Mn–Cr)AlGe films, respectively, with an optimum annealing temperature of 400 °C and Mg-insertion thicknesses of 1.4 and 3.0 nm for the top and bottom interfaces, respectively. The Mg insertions were relatively thick compared with results of similar studies of the insertion effect on magnetic tunnel junctions. Cross-sectional transmission electron microscope images revealed that the Mg-insertion layers acted as barriers to the interdiffusion of Al atoms as well as oxidization from the MgO layers. The K u at a few-nanometer thicknesses was comparable to or higher than those reported for perpendicularly magnetized CoFeB films, which are conventionally used in MRAMs, whereas the M s value was one third or smaller than those of the CoFeB films. The developed (Mn–Cr)AlGe films are promising materials because of their magnetic properties and their compatibility to the silicon process in film fabrication. [ABSTRACT FROM AUTHOR]

Magnetic thin films showing high perpendicular magnetic anisotropy, Ku, and low saturation magnetization, Ms, are essential for realizing a small switching current in spintronic devices utilizing the current induced magnetization switching phenomena. The Cu2Sb-type MnAlGe intermetallic compound is a material showing uniaxial magnetocrystalline anisotropy with a relatively low Ms, which is attractive for spintronic application. In this study, the layer thickness dependence of Ku was investigated in poly-crystalline MnAlGe films, and the MgO template effect is discussed to achieve perpendicularly magnetized films in a few-nanometer thickness range. Experimental results suggested that the (001)-texture for the perpendicular magnetization was promoted by the MgO(001) template through the solid-phase epitaxy growth by annealing, which is similar with that in conventionally used CoFeB|MgO layered samples. Ku of about 2 × 106 erg/cm3 was achieved in a 5 nm-thick MnAlGe film using MgO buffer and capping exhibiting a low Ms value of approximately 200 emu/cm3 at room temperature. Although the magnitude of Ku is still in a moderate range, the low Ms is a promising feature for spintronic application. [ABSTRACT FROM AUTHOR]

A perpendicularly magnetized film is essentially important for spintronics applications, such as spin-transfer-torque type magnetoresistive random access memories, STT-MRAMs, and large perpendicular anisotropy energy, K u , with small saturation magnetization, M s , is required for reducing the critical current for the STT induced magnetization switching phenomenon. In this study, an equiatomic intermetallic compound, MnGaGe, was investigated in epitaxially grown film samples. Perpendicularly magnetized films with an M s value of about 260 emu/cm3 at 300 K were fabricated onto MgO (100) single crystal substrates. The maximum value of K u was 8.1 × 106 erg/cm3 at room temperature. Microstructure analysis using a scanning transmission electron microscope atomically revealed the Cu2Sb type crystal structure in the film sample. First principles calculations were also carried out to discuss the electronic structure. Using the analysis of the projected density of states for 3d-orbitals, the hybridization of the 3d-orbitals was suggested as a possible factor for promoting magnetocrystalline anisotropy. The MnGaGe film with the large K u and relatively small M s would be potentially used for spintronics applications. [ABSTRACT FROM AUTHOR]

Cu2Sb-type intermetallic compound, MnAlGe, is known to exhibit uniaxial magnetocrystalline anisotropy and relatively small saturation magnetization, which is suitable for spintronic application, e.g. spin-transfer phenomena requiring small critical current density. Ge-concentration dependence of the crystal structures, saturation magnetization, Ms, and perpendicular magnetic anisotropy, Ku was investigated for MnAlGe films prepared onto silicon substrates with a thermally oxidized amorphous layer. For the stoichiometric and Ge-rich samples, the films exhibited (001)-texture with perpendicular magnetization. The maximum values of Ms and Ku were 270 emu/cm3 and 4.8 × 106 erg/cm3, respectively, which were comparable values with those reported for bulk and epitaxially grown films in literatures. [ABSTRACT FROM AUTHOR]

Buffer-layer dependences of dead-layer thickness, saturation magnetization ( M\mathrm {s}) , and interface magnetic anisotropy ( K\mathrm {s}) were systematically investigated for Co2Fe0.4Mn0.6Si (CFMS) Heusler alloy ultrathin films with Pd, Ru, and Cr buffer layers. Perpendicular magnetization was only achieved in 0.6 and 0.8 nm-thick CFMS ultrathin films deposited on Pd buffer layer and annealed at 400 °C. At the optimum annealing temperature of 400 °C, K\mathrm {{s}} of 1.2 erg/cm2 was obtained for the Pd buffer layer, which was 3–6 times larger than those for Ru and Cr buffer layers. The difference in K\mathrm {{s}} probably originates from the interdiffusion and different crystallized compounds at the interface between Pd (Ru, Cr) and CFMS layers. [ABSTRACT FROM AUTHOR]