2005 APS March Meeting
Monday–Friday, March 21–25, 2005;
Los Angeles, CA
Session V10: Focus Session: Spin Injection into Semiconductors
11:15 AM–1:51 PM,
Thursday, March 24, 2005
LACC
Room: 153B
Sponsoring
Units:
DMP GMAG
Chair: Chris Palmstrom, University of Minnesota
Abstract ID: BAPS.2005.MAR.V10.4
Abstract: V10.00004 : Electrical Spin Injection into InAs/GaAs Quantum Dots at Room Temperature*
11:51 AM–12:27 PM
Preview Abstract
Abstract
Author:
Connie H. Li
(Naval Research Lab)
Efficient electrical injection of spin-polarized electrons from a
magnetic
contact into a semiconductor is an essential requirement for
utilizing the
spin degree of freedom in semiconductor spintronic devices. The
spin-
polarized light emitting diode (spin-LED) is used as the platform
for
demonstrating spin injection since it provides a quantitative and
model
independent measure of the electron spin polarization. Using this
method, we have observed an electron spin polarization 32\% in GaAs
(001) QWs due to electrical spin injection across an Fe/AlGaAs
reverse-
biased Schottky contact [1].
Recent attention has focused on the unpaired spin of an electron
in a
charged quantum dot (QD). The lack of available energy states due to
the discrete energy level spectrum inhibits both elastic spin
flip and
inelastic phonon scattering mechanisms, resulting in long spin
relaxation times [2]. This is an important requirement for
developing
spin-based electronics and certain implementations of quantum
information technology. We report here room temperature electron
spin
polarization in InAs/GaAs self assembled QDs by electrical
injection of
spin-polarized electrons from an Fe Schottky contact.
The quantum dots, formed by Stranski-Krastanov strain driven self-
assembly during MBE growth, are embedded in the intrinsic region
of an
AlGaAs/GaAs QW LED structure with an epitaxial Fe film as the
surface
contact for injection of spin-polarized electrons. The circular
polarization of the QD electroluminescence tracks the out-of-plane
magnetization of the Fe, and shows that a 5\% electron spin
polarization
is achieved in the InAs QDs. The QD spin polarization persists
to room
temperature. Nonmagnetic reference samples show a background
polarization on the order of 1\% which has little dependence on
magnetic field. TEM images indicate that the Fe/AlGaAs interface is
rougher than expected possibly due to QD incorporation, which is
likely
to limit spin injection, and may be solved by refining growth
procedures.
These results demonstrate that practical regimes of spin-based
operation are clearly attainable in solid state semiconductor
devices.
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[1] A.T. Hanbicki et al., APL 80, 1240 (2002), 82, 4092 (2003).
[2] M. Paillard et al. PRL 86, 1634(2001).
*Work in collaboration with G. Kioseoglou, O. M. J. van ’t Erve, M. E. Ware, D. Gammon, R. M. Stroud, B. T. Jonker at the Naval Research Lab, and R. Mallory, M. Yasar, A. Petrou at SUNY Buffalo. Supported by DARPA (SPINS Program), ONR, and NSF
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2005.MAR.V10.4