Optical Pumping and Optical Detection of Spin-Polarized Electrons in a Conduction Band

1971 ◽  
Vol 49 (14) ◽  
pp. 1850-1860 ◽  
Author(s):  
R. R. Parsons
Keyword(s):  
Magnetic Field ◽  
Conduction Band ◽  
Spin Polarization ◽  
Optical Pumping ◽  
Polarized Light ◽  
Degree Of Polarization ◽  
Polarized Electrons ◽  
Excitation Light ◽  
Circularly Polarized Light ◽  
Spin Polarized

Spin-polarized electrons are created in the conduction band of p-type GaSb by excitation with σ+ or σ− circularly polarized light. The degree of polarization of the photoluminescence is used to measure the optically pumped spin polarization. The measurements as a function of transverse magnetic field yield the spin-relaxation time and the lifetime of the photocreated electrons. The degree of polarization oscillates as a function of the photon energy of the excitation light. This effect is associated with mechanisms of rapid energy loss involving optical and acoustical phonons. The optical pumping is studied as a function of temperature in the range 3.5 °K ≤ T ≤ 11 °K. A maximum spin polarization [Formula: see text] is obtained at [Formula: see text]. The efficiency of the optical pumping is significantly increased with the application of a weak longitudinal magnetic field.

Optical Pumping of Spin-Polarized Conduction Electrons and Inelastic Scattering by Neutral Acceptors

1973 ◽  
Vol 51 (7) ◽  
pp. 718-723 ◽  
Author(s):  
R. R. Parsons
Keyword(s):  
Inelastic Scattering ◽  
Spin Polarization ◽  
Optical Pumping ◽  
Polarized Light ◽  
Energy Relaxation ◽  
Degree Of Polarization ◽  
Conduction Band Edge ◽  
Circularly Polarized Light ◽  
Conduction Electrons ◽  
Spin Polarized

The energy relaxation mechanisms of conduction electrons in p-type GaSb at 1.9 °K are investigated by an optical pumping technique. Spin-polarized electrons are excited across the forbidden band gap with circularly polarized light. The number of photocreated electrons is obtained from the intensity of the photoluminescence; and the spin polarization from the degree of polarization of the photoluminescence. The experiment shows that the number of electrons and the spin polarization at the conduction band edge depend on the initial energy of the electrons and on the number of neutral acceptors. An explanation of the results is given in terms of two processes of energy relaxation for conduction electrons: (i) the emission of longitudinal optical phonons, and (ii) inelastic scattering by neutral acceptors.

Nuclear spin polarization by out-of-plane spin injection from ferromagnet into an InAs heterostructure

2012 ◽  
Vol 1396 ◽  
Author(s):  
Tomotsugu Ishikura ◽  
Takahiro Hiraki ◽  
Takashi Matsuda ◽  
Joungeob Lee ◽  
Kanji Yoh
Keyword(s):  
Magnetic Field ◽  
Spin Polarization ◽  
Nuclear Spin ◽  
Spin Injection ◽  
Hall Voltage ◽  
Nuclear Spin Polarization ◽  
Polarized Electrons ◽  
Spin Polarized ◽  
Magnetic Metal ◽  
Out Of Plane

AbstractWe have investigated an InAs channel Hall-bar structure with ferromagnetic spin injector in one of the current terminals. After magnetizing the Fe electrode, spin polarized electrons are injected through the edge of the isolation mesa structure and the anomalous Hall voltage is observed, when electrons are injected from the ferromagnetic terminal. However, when electrons are injected from the non-magnetic metal (Ti/Au) of opposite terminal, the Hall voltage disappeared to the variation error level due to the fabrication imperfections. This result suggests the possibility that out-of-plane spin injection from the channel edge lead to perpendicular nuclear magnetic field. It is presumably caused by nuclear spin polarization in InAs channel near the spin source edge through Overhauser effect. The estimated internal magnetic field was 2000 Gauss.

EXCITON SPIN STATES IN NANOCRYSTAL QUANTUM DOTS REVEALED BY SPIN-POLARIZED RESONANT PHOTOLUMINESCENCE AND RAMAN SPECTROSCOPY

2004 ◽  
Vol 18 (27n29) ◽  
pp. 3769-3774 ◽  
Author(s):  
MADALINA FURIS ◽  
TODD BARRICK ◽  
PATRICK ROBBINS ◽  
SCOTT A. CROOKER ◽  
MELISSA PETRUSKA ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Quantum Dots ◽  
Magnetic Fields ◽  
High Field ◽  
Polarized Light ◽  
Zero Magnetic Field ◽  
Spin States ◽  
Circularly Polarized Light ◽  
Spin Polarized ◽  
Nanocrystal Quantum Dots

We performed spin-polarized resonant Raman and resonant photoluminescence excitation spectroscopy (also known as "fluorescence line narrowing") on ZnS -capped CdSe nanocrystal quantum dots in high magnetic fields to 33 Tesla and temperatures down to 1.7K, which allows detailed investigation of the excitonic spin states. In these experiments, spin-polarized electrons and holes are resonantly injected by circularly polarized light into colloidal quantum dots of specific size, using a narrowband tunable dye laser and a fiber-coupled probe that is specially-designed for use in high-field magnets. In addition to the expected broad features associated with excitonic recombination and Raman-like peaks associated with quantized acoustic phonons, the photoluminescence spectra measured at magnetic fields larger than 10 Tesla develop a sharp peak, which moves roughly linearly with applied magnetic field. Further, the energy of this high-field peak varies systematically as a function of nanocrystal size. However, unlike typical electron spin flip transitions, the mode energy extrapolates to a finite value at zero magnetic field, suggesting the existence of an additional size-dependent exchange mechanism.

Optically Induced and Detected Spin Current

2017 ◽  
Author(s):  
A. Hirohata ◽  
J.-Y. Kim
Keyword(s):  
Band Gap ◽  
Polarized Light ◽  
Spin Current ◽  
Polarized Electrons ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Spin Polarized ◽  
Electron Hole Pair ◽  
Tunnelling Microscopy ◽  
Optically Induced

This chapter presents an alternative method of injecting spin-polarized electrons into a nonmagnetic semiconductor through photoexcitation. This method uses circularly-polarized light, whose energy needs to be the same as, or slightly larger than, the semiconductor band-gap, to excite spin-polarized electrons. This process will introduce a spin-polarized electron-hole pair, which can be detected as electrical signals. Such an optically induced spin-polarized current can only be generated in a direct band-gap semiconductor due to the selection rule described in the following sections. This introduction of circularly polarized light can also be used for spin-polarized scanning tunnelling microscopy.

CHARACTERIZATION OF THE MAGNETIC STRUCTURE OF Cr on Pd(001) BY SPIN-POLARIZED AND ANGLE-RESOLVED PHOTOELECTRON DIFFRACTION

1997 ◽  
Vol 04 (06) ◽  
pp. 1263-1265 ◽  
Author(s):  
P. RENNERT ◽  
W. HERGERT ◽  
W. MÜCK ◽  
A. CHASSÉ
Keyword(s):  
Magnetic Structure ◽  
Spin Polarization ◽  
Polarized Light ◽  
Normal Incidence ◽  
Magnetic Scattering ◽  
Circularly Polarized Light ◽  
Photoelectron Diffraction ◽  
Antiferromagnetic Structure ◽  
Spin Polarized ◽  
Essential Contribution

Recent investigations of the magnetic structure of Cr layers on Pd (001) have shown that two structures appear dependent on the number of Cr layers which have an in-plane antiferromagnetic structure and a layer antiferromagnetic structure, respectively. It is shown that these magnetic structures should be distinguishable experimentally by spin-polarized photoelectron diffraction experiments. The photoelectron intensity from the Cr 2 p 1/2 core level is calculated for normal incidence of left and right circularly polarized light. It is shown that there is a strong dichroism and spin polarization in the intensities. Dichroism and spin polarization are analyzed with respect to their sources, and thus the contribution of the magnetic scattering is separated. It is an essential contribution for a monolayer Cr on Pd (001).

High Spin Polarization of Conduction Band Electrons in GaAs-GaAsP Strained Layer Superlattice Fabricated as a Spin-Polarized Electron Source

2004 ◽  
Vol 43 (6A) ◽  
pp. 3371-3375 ◽  
Author(s):  
Tetsuya Matsuyama ◽  
Hisaya Takikita ◽  
Hiromichi Horinaka ◽  
Kenji Wada ◽  
Tsutomu Nakanishi ◽  
...  
Keyword(s):  
Conduction Band ◽  
Spin Polarization ◽  
High Spin ◽  
Electron Source ◽  
Strained Layer ◽  
Spin Polarized ◽  
High Spin Polarization ◽  
Strained Layer Superlattice

scholarly journals Scanning-Ion Microscopy with Polarization Analysis (Simpa)

1993 ◽  
Vol 313 ◽  
Author(s):  
N. J. Zheng ◽  
C. Rau
Keyword(s):  
High Resolution ◽  
Spin Polarization ◽  
Imaging Technique ◽  
Ion Beam ◽  
Polarization Analysis ◽  
Polarized Electrons ◽  
Magnetic Structures ◽  
Magnetic Imaging ◽  
Spin Polarized ◽  
Ion Microscopy

ABSTRACTWe have developed a novel, high-resolution magnetic imaging technique, scanning-ion microscopy with polarization analysis (SIMPA). In SIMPA, a highly-focused, scanning Ga+ ion beam is used to excite spin-polarized electrons at surfaces of ferromagnetic Materials. By Measuring the intensity and the spin polarization of the emitted electrons using a newly developed, compact mott polarimeter, topographic and magnetic images of magnetic structures are obtained. We report on first SIMPA studies on single-crystalline Fe samples.

Spin-polarization effects in Cherenkov radiation from electrons

2020 ◽  
Vol 98 (7) ◽  
pp. 660-663
Author(s):  
A.A. Peshkov
Keyword(s):  
Spin Polarization ◽  
Cherenkov Radiation ◽  
Stokes Parameters ◽  
Electron Spin Polarization ◽  
Polarized Electrons ◽  
Small Component ◽  
Polarization Effects ◽  
Spin Polarized ◽  
Linearly Polarized ◽  
Spin Polarization Effects

A quantum electrodynamical theory of Cherenkov radiation emitted by spin-polarized electrons moving in an isotropic medium is developed within the density matrix framework. Special attention is paid to the polarization properties of the emitted photons described by means of Stokes parameters. It is demonstrated that, although the Cherenkov radiation is primarily linearly polarized in the plane containing the direction of observation and the path of the electrons, the photons may have a small component of circular polarization of the order of 3 × 10−6 for electron kinetic energy of 500 keV due to the initial electron spin polarization, whose existence can be confirmed by sensitive measurements in the future.

scholarly journals Demonstration of polarization control GaN-based micro-cavity lasers using a rigid high-contrast grating reflector

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Tsu-Chi Chang ◽  
Kuo-Bin Hong ◽  
Shuo-Yi Kuo ◽  
Tien-Chang Lu
Keyword(s):  
Semiconductor Lasers ◽  
Optical Pumping ◽  
Polarized Light ◽  
Transverse Magnetic ◽  
Bragg Reflector ◽  
Degree Of Polarization ◽  
High Contrast ◽  
Distributed Bragg Reflector ◽  
Output Mirror ◽  
High Contrast Grating

Abstract We reported on GaN microcavity (MC) lasers combined with one rigid TiO2 high-contrast grating (HCG) structure as the output mirror. The HCG structure was directly fabricated on the GaN structure without an airgap. The entire MC structure comprised a bottom dielectric distributed Bragg reflector; a GaN cavity; and a top HCG reflector, which was designed to yield high reflectance for transverse magnetic (TM)- or transverse electric (TE)-polarized light. The MC device revealed an operation threshold of approximately 0.79 MW/cm2 when pulsed optical pumping was conducted using the HCG structure at room temperature. The laser emission was TM polarized with a degree of polarization of 99.2% and had a small divergence angle of 14° (full width at half maximum). This laser operation demonstration for the GaN-based MC structure employing an HCG exhibited the advantages of HCGs in semiconductor lasers at wavelengths from green to ultraviolet.

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