Epitaxial growth of MgO barrier on Si is of technological importance due to the symmetry filtering effect of the MgO barrier in conjunction with bcc-ferromagnets. We study the epitaxial growth of MgO on (100)-Si by molecular beam epitaxy. MgO matches Si with 4:3 cell ratio, which renders Fe to be 45° rotated relative to Si, in sharp contrast to the direct epitaxial growth of Fe on Si. The compressive strains from Si lead to the formation of small angle grain boundaries in MgO below 5nm, and also affect the transport characteristics of Fe∕MgO∕Fe magnetic tunnel junctions formed on top.

We investigate the spin-orbit induced spin-interference pattern of ballistic electrons traveling along any regular polygon. It is found that the spin interference depends strongly on the Rashba and Dresselhaus spinorbit constants as well as on the sidelength and alignment of the polygon. We derive the analytical formulas for the limiting cases of either zero Dresselhaus or zero Rashba spin-orbit coupling, including the result obtained for a circle. We calculate the nonzero Dresselhaus and Rashba case numerically for the square, triangle, hexagon, and circle and discuss the observability of the spin interference which can potentially be used to measure the Rashba and Dresselhaus coefficients.

The efficiency of spin polarized charge transfer was investigated in an Fe/MgO tunnel barrier/GaAs based structure using spin dependent photocurrent measurements, whereby a spin imbalance in carrier population was generated in the GaAs by circularly polarized light. The dominance of tunneling transport processes over Schottky emission gave rise to a high spin transfer efficiency of 35% under the photovoltaic mode of device operation. A spin dependent tunneling conductance associated with spin polarized electron transport was identified by the observation of phase changes. This transport prevails over the unpolarized electron and hole conduction over the bias range which corresponds to flat band conditions.

The evaporating electron gun in UHV systems has a side-effect that it gives rise to large quantities of scattered and secondary electrons. These electrons may cause damage to sensitive samples and may yield lift-off problems of resist defined patterns. We designed an electron deflector to deflect the electrons and measured the current caused by the electrons during the evaporation of iron.

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