77 research outputs found
Voltage-Controlled Spin Selection in a Magnetic Resonant Tunnelling Diode
We have fabricated all II-VI semiconductor resonant tunneling diodes based on
the (Zn,Mn,Be)Se material system, containing dilute magnetic material in the
quantum well, and studied their current-voltage characteristics. When subjected
to an external magnetic field the resulting spin splitting of the levels in the
quantum well leads to a splitting of the transmission resonance into two
separate peaks. This is interpreted as evidence of tunneling transport through
spin polarized levels, and could be the first step towards a voltage controlled
spin filter.Comment: To be published in Phys. Rev. Let
Self Assembled II-VI Magnetic Quantum Dot as a Voltage-Controlled Spin-Filter
A key element in the emergence of a full spintronics technology is the
development of voltage controlled spin filters to selectively inject carriers
of desired spin into semiconductors. We previously demonstrated a prototype of
such a device using a II-VI dilute-magnetic semiconductor quantum well which,
however, still required an external magnetic field to generate the level
splitting. Recent theory suggests that spin selection may be achievable in
II-VI paramagnetic semiconductors without external magnetic field through local
carrier mediated ferromagnetic interactions. We present the first experimental
observation of such an effect using non-magnetic CdSe self-assembled quantum
dots in a paramagnetic (Zn,Be,Mn)Se barrier.Comment: 4 pages, 4 figure
Electric field control of magnetization dynamics in ZnMnSe/ZnBeSe diluted-magnetic-semiconductor heterostructures
We show that the magnetization dynamics in diluted magnetic semiconductors
can be controlled separately from the static magnetization by means of an
electric field. The spin-lattice relaxation (SLR) time of magnetic Mn2+ ions
was tuned by two orders of magnitude by a gate voltage applied to n-type
modulation-doped (Zn,Mn)Se/(Zn,Be)Se quantum wells. The effect is based on
providing an additional channel for SLR by a two-dimensional electron gas
(2DEG). The static magnetization responsible for the giant Zeeman spin
splitting of excitons was not influenced by the 2DEG density
Molecular-beam epitaxy of (Zn,Mn)Se on Si(100)
We have investigated the growth by molecular-beam epitaxy of the II-VI
diluted magnetic semiconductor (Zn,Mn)Se on As-passivated Si(100) substrates.
The growth start has been optimized by using low-temperature epitaxy. Surface
properties were assessed by Nomarski and scanning electron microscopy. Optical
properties of (Zn,Mn)Se have been studied by photoluminescence and a giant
Zeeman splitting of up to 30 meV has been observed. Our observations indicate a
high crystalline quality of the epitaxial films.Comment: To be published in Applied Physics Letter
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