On the Pulsed Laser Deposition of Single-Crystal Films of CoFeMnSi Heusler Alloy on a MgO Substrate

For the creation of modern spintronic devices, heterostructures based on the spin gapless semiconductor CoFeMnSi are of interest. The characteristics of such devices are determined by the structural and magnetic properties of the CoFeMnSi layer. The development of a technology for the production of defect-free thin-film layers of CoFeMnSi is an urgent task at present. The paper considers thin single-crystal CoFeMnSi films grown on the surface of a MgO(100) substrateby the pulsed laser deposition method. Optimization of the technological parameters for the production of CoFeMnSi films is carried out. It is shown that by selecting the optimal values of the MgO(100) substrate temperature, the target-substrate distance, and the energy and frequency of the pulsed laser radiation, CoFeMnSi films can be produced in the island or layer-plus-island growth modes. It is found that for to grow CoFeMnSi films in the layer-by-layer mode, it is necessary to introduce two-minute pauses during the formation of each new film layer, the use of which makes it possible to grow atomically smooth single-crystal CoFeMnSi films up to 20 nm thick. Electron microscopic studies and diffraction analysis of cross-sectional samples of the films grown on the substrate demonstrate that they have a perfect cubic crystalline structure. The position of the reflections in the diffraction pattern indicates that the cubic unit cells of the CoFeMnSi film (space group F (4) over bar 3m) and the MgO(100) crystal are rotated relative to each other by an angle of 45 degrees around the MgO[001] direction, thereby ensuring their alignment along the CoFeMnSi(202) and MgO(020) planes. The obtained results can be used for the production of multilayer heterostructures and devices based on them.