Dresden 2011 – scientific programme

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MA: Fachverband Magnetismus

MA 49: Spin-dependent Transport/ Spin Torque

MA 49.2: Talk

Thursday, March 17, 2011, 11:00–11:15, HSZ 04

EuS Spin Filter Tunnel Contacts to Silicon with various doping concentrations — •H. Doganay, M. Müller, R. Schreiber, and C. M. Schneider — IFF-9, FZ Jülich

Utilizing spin filter (SF) materials as tunnel barrier is a unique method to generate highly spin-polarized currents. We studied electrical and magnetic properties of EuS SF tunnel contacts to silicon with the emphasis of different Si doping concentrations. First, we explored the magnetic properties of EuS on Si(100) in thickness regime of tunnel barriers. Our studies indicated that thin EuS/Si films exhibit bulk-like magnetic properties above d≥ 3 nm [1]. Furthermore, we studied the morphology of Si/EuS(d=1− 6nm)/Au sample surfaces by AFM and found that magnetization M correlates with roughness. We investigated the electrical transport properties across EuS/Si(100) interfaces for different n-Si doping concentrations. Transport experiments on Si(100)/Au junctions revealed the respective Schottky barrier profile. We analyzed both spin injection and -detection conditions of R(T) and I(V) characteristics of EuS/Si(100) contacts. By fitting the temperature-dependent I(V) characteristics we determined the exchange splitting of a 4 nm thick EuS SF barrier as 0.30eV, which is comparable to the bulk value (ΔE_xc(EuS_bulk)=0.36eV). Moreover, we found that SF in EuS/Si is bias-dependent, with the maximum tunneling SP occurring at medium bias voltages (0.40 < V < 0.70). In summary, our experiments demonstrate a successful integration EuS as a tunnel barrier to n-Si(100) for different n-Si doping concentrations.[1] M. Müller et al., submitted to JAP