Regensburg 2000 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 44: II-VI Halbleiter

HL 44.6: Vortrag

Freitag, 31. März 2000, 11:45–12:00, H17

Semimagnetic resonant tunneling structures for manipulating spin-polarized electron current — •Thomas Gruber, Markus Keim, Roland Fiederling, Guenter Reuscher, Andreas Waag, Georg Schmidt, and Laurens Molenkamp — Physikalisches Institut EP III, Am Hubland, 97074 Wuerzburg

We report on the fabrication of BeTe/ZnMnSe/BeTe double barrier

resonant tunneling structures (RTS), which can be used for an

efficient injection of a spin-polarized electron current into

GaAs. The RTSs were grown on AlGaAs/GaAs p–i–n LEDs, which

serve as a detector of the spin-polarization of the injected

current via the polarization of the emitted light. The RTSs as

well as the LEDs were grown in an interconnetcted two chamber

MBE system. The sp-d exchange interaction of the anti-

ferromagnetically coupled magnetic Mn ions incorporated into

the quantum well leads to a giant g-factor of up to 100, and

hence a large Zeeman-splitting in external magnetic fields.

Scattering phenomena cause the electrons to relax into the

spin-down states and therefore create a spin-polarized electron

current injected into the AlGaAs/GaAs LED – analysis of the

emitted light depicts a spin-polarization of up to 70%.

More work is underway to examine the possible use of RTSs

as an electrically tunable spin filter device.