Wim Van Roy

Adhesively bonded Ce:YIG/SOI integrated optical circulator

A classical 3-port optical circulator is demonstrated on the silicon-on-insulator (SOI) platform. A garnet die with a magneto-optical cerium-doped yttrium iron garnet (Ce:YIG) layer is bonded on top of a Mach-Zehnder interferometer circuit using a thin adhesive bonding layer. The power transmission between different ports is characterized in the presence of an external magnetic field, transversal to the light propagation direction. An isolation of 22 dB is measured at a wavelength of 1562 nm.

Highly efficient room temperature spin injection in a metal-insulator-semiconductor light-emitting diode

We demonstrate highly efficient spin injection at low and room temperature in an AlGaAs/GaAs semiconductor heterostructure from a CoFe/AlOX tunnel spin injector. We use a double-step oxide deposition for the fabrication of a pinhole-free AlOX tunnel barrier. The measurements of the circular polarization of the electroluminescence in the Oblique Hanle Effect geometry reveal injected spin polarizations of at least 24% at 80 K and 12% at room temperature.

Spin dependent transport properties in spin-LEDs: a survey

Optical characterization is a powerful tool for assessment of spin-injection properties in spin-LEDs. We show a comparison of spin-dependent transport properties in LEDs with different spin-injector structures including ferromagnet/tunnel-barrier or Schottky-barrier injectors and magnetic semiconductors. Using these devices, room temperature spin-injection and voltage-controlled injection has been achieved. The optical technique used is the Oblique Hanle Effect. Features such as spin-nuclear interactions can be clearly demonstrated in such spin-LED structures. Finally we discuss the design of a spin-dependent contact that can supply both electrical spin injection as electrical spin detection.