Spin dynamics of two-dimensional electrons in a quantum Hall system probed by time-resolved Kerr rotation spectroscopy

2008 ◽  
Vol 78 (4) ◽  
Author(s):  
D. Fukuoka ◽  
T. Yamazaki ◽  
N. Tanaka ◽  
K. Oto ◽  
K. Muro ◽  
...  
Keyword(s):  
Spin Dynamics ◽  
Quantum Hall ◽  
Two Dimensional ◽  
Kerr Rotation ◽  
Time Resolved ◽  
Quantum Hall System

Time-Resolved Kerr Rotation Spectroscopy of Spin Dynamics in a Quantum Hall System

2010 ◽  
Author(s):  
D. Fukuoka ◽  
N. Tanaka ◽  
K. Oto ◽  
K. Muro ◽  
Y. Hirayama ◽  
...  
Keyword(s):  
Spin Dynamics ◽  
Quantum Hall ◽  
Kerr Rotation ◽  
Time Resolved ◽  
Quantum Hall System

Superfluidity of the Lattice Anyon Gas

1989 ◽  
Vol 03 (12) ◽  
pp. 1965-1995 ◽  
Author(s):  
Eduardo Fradkin
Keyword(s):  
Quantum Hall ◽  
Goldstone Mode ◽  
Two Dimensional ◽  
Hall Conductance ◽  
Dimensional Lattice ◽  
Quantum Hall Systems ◽  
Wigner Transformation ◽  
Topological Invariance ◽  
Quantum Hall System ◽  
Chern Simons

I consider a gas of “free” anyons with statistical paremeter δ on a two dimensional lattice. Using a recently derived Jordan-Wigner transformation, I map this problem onto a gas of fermions on a lattice coupled to a Chern-Simons gauge theory with coupling [Formula: see text]. I show that if [Formula: see text] and the density [Formula: see text], with r and q integers, the system is a superfluid. If q is even and the system is half filled the state may be either a superfluid or a Quantum Hall System depending on the dynamics. Similar conclusions apply for other values of ρ and δ. The dynamical stability of the Fetter-Hanna-Laughlin goldstone mode is insured by the topological invariance of the quantized Hall conductance of the fermion problem. This leads to the conclusion that anyon gases are generally superfluids or quantum Hall systems.

GENERATING and MANIPULATING SPINS IN SEMICONDUCTORS

2008 ◽  
Vol 22 (01n02) ◽  
pp. 109-110
Author(s):  
DAVID D. AWSCHALOM
Keyword(s):  
Hall Effect ◽  
Spin Polarization ◽  
Electron Spin ◽  
Quantum Confinement ◽  
Spin Dynamics ◽  
Spin Hall Effect ◽  
Spin Orbit ◽  
Two Dimensional ◽  
Kerr Rotation ◽  
Bulk Semiconductors

Spin-orbit coupling in semiconductors relates the spin of an electron to its momentum, and provides a pathway for electrically initializing and manipulating electron spins for applications in spintronics and spin-based quantum information processing. This coupling can be regulated with strain in bulk semiconductors and quantum confinement in semiconductor heterostructures. We will provide an overview of optical studies exploring spin dynamics in conventional and magnetic semiconductors, followed by recent experiments probing all-electrical generation and manipulation of spins. Using Faraday and Kerr rotation magneto-optical spectroscopies with temporal and spatial resolution, current-induced spin polarization1 and the spin Hall effect2 have been observed using both spatially-resolved and temporally-resolved techniques in bulk semiconductors. More recently, we have investigated the spin Hall effect and current-induced spin polarization in two-dimensional electron gases confined in (110) AlGaAs quantum wells using Kerr rotation microscopy.3 In marked contrast to previous measurements in three dimensional systems, the spin Hall profile in two dimensions shows a surprisingly complex structure and the current-induced spin polarization is out-of-plane. The experiments map the strong dependence of the current-induced spin polarization to the crystal axis along which the electric field is applied, reflecting the anisotropy of the spin-orbit interaction. The effect of reducing feature sizes in electrical spintronic devices is relevant for future technological applications. To this end, we discuss related measurements probing electron spin dynamics in narrow two-dimensional InGaAs quantum well wires with widths ranging from the micron to the submicron scale.4 The data reveal a surprising slowing of the electron spin relaxation in reduced geometries. These results reveal opportunities for tuning a spin source using quantum confinement, strain and device engineering in non-magnetic materials. This work was supported by the ARO, DARPA, NSF and ONR. Note from Publisher: This article contains the abstract only.

Two-dimensional localization in the presence of random flux and the quantum Hall system at even-denominator filling fractions

1993 ◽  
Vol 48 (15) ◽  
pp. 11095-11106 ◽  
Author(s):  
Vadim Kalmeyer ◽  
Dan Wei ◽  
Daniel P. Arovas ◽  
Shoucheng Zhang
Keyword(s):  
Quantum Hall ◽  
Two Dimensional ◽  
Quantum Hall System

Spin Relaxation in GaAs Doped with Magnetic (Mn) Atoms

2010 ◽  
Vol 168-169 ◽  
pp. 47-54
Author(s):  
Ilya A. Akimov ◽  
G.V. Astakhov ◽  
R.I. Dzhioev ◽  
K.V. Kavokin ◽  
V.I. Korenev ◽  
...  
Keyword(s):  
Spin Relaxation ◽  
Degrees Of Freedom ◽  
Spin Dynamics ◽  
Point Of View ◽  
Magnetic Impurities ◽  
Kerr Rotation ◽  
Time Resolved ◽  
G Factor ◽  
Theoretical Predictions ◽  
The Magnetic Field

The GaAs doped with donors manifests long times of spin relaxation, while in the case of acceptors (or magnetic impurities) spin relaxation rate increases markedly, in accordance with theoretical predictions. From the practical point of view, this situation is unfavorable, since the devices based on spin degrees of freedom require long times of the spin memory. Therefore semiconductors such as p-GaAs were not considered as promising materials for spintronics. In the present work this conclusion is refuted by means of investigation of the spin dynamics of electrons in epitaxial layers of gallium arsenide doped with Mn impurities. In spite of the expectations, we have discovered the suppression of the spin relaxation of electrons in GaAs:Mn by two orders of magnitude. This effect is a consequence of compensation of the hole and manganese effective magnetic fields due to the antiferromagnetic interaction. The analogous results obtained for the case of GaAs quantum well doped with Mn [R. C. Myers, et al., Nature Materials 7, 203 (2008)] were interpreted as the result of the spin precession of magnetic acceptors rather than electrons. Through separate measurements of g-factor by means of time resolved spectroscopy it has been proved that long times of spin relaxation in p-GaAs:Mn relate to electrons and not to magnetic acceptors. The oscillation frequency of the angle of Kerr rotation depends linearly on the magnetic field and complies with g=0.46±0.02, i.e. the electronic g-factor.

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