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.

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.

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).

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.

scholarly journals Polarized proton beams from laser-induced plasmas

2019 ◽  
Vol 7 ◽  
Author(s):  
Anna Hützen ◽  
Johannes Thomas ◽  
Jürgen Böker ◽  
Ralf Engels ◽  
Ralf Gebel ◽  
...  
Keyword(s):  
Laser System ◽  
Polarized Light ◽  
Particle Beam ◽  
Degree Of Polarization ◽  
Acceleration Process ◽  
Simulation Code ◽  
Experimental Realization ◽  
Circularly Polarized Light ◽  
Spin Effects ◽  
Polarized Proton

We report on the concept of an innovative source to produce polarized proton/deuteron beams of a kinetic energy up to several GeV from a laser-driven plasma accelerator. Spin effects have been implemented into the particle-in-cell (PIC) simulation code VLPL (Virtual Laser Plasma Lab) to make theoretical predictions about the behavior of proton spins in laser-induced plasmas. Simulations of spin-polarized targets show that the polarization is conserved during the acceleration process. For the experimental realization, a polarized HCl gas-jet target is under construction using the fundamental wavelength of a Nd:YAG laser system to align the HCl bonds and simultaneously circularly polarized light of the fifth harmonic to photo-dissociate, yielding nuclear polarized H atoms. Subsequently, their degree of polarization is measured with a Lamb-shift polarimeter. The final experiments, aiming at the first observation of a polarized particle beam from laser-generated plasmas, will be carried out at the 10 PW laser system SULF at SIOM, Shanghai.

scholarly journals Photoemission ofBi2Se3with Circularly Polarized Light: Probe of Spin Polarization or Means for Spin Manipulation?

2014 ◽  
Vol 4 (1) ◽  
Author(s):  
J. Sánchez-Barriga ◽  
A. Varykhalov ◽  
J. Braun ◽  
S.-Y. Xu ◽  
N. Alidoust ◽  
...  
Keyword(s):  
Spin Polarization ◽  
Polarized Light ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Spin Manipulation ◽  
Light Probe

Linear and Circular Dichroism in Angle Resolved Fe 3p Photoemission

1994 ◽  
Vol 375 ◽  
Author(s):  
E. Tamura ◽  
G. D. Waddill ◽  
J. G. Tobin ◽  
P. A. Sterne
Keyword(s):  
Polarized Light ◽  
Exchange Splitting ◽  
Orbit Splitting ◽  
Green Function Method ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
X Ray ◽  
Spin Orbit Splitting ◽  
Magnetic Dichroism ◽  
Spin Polarized

AbstractUsing a recently developed spin-polarized, fully relativistic, multiple scattering approach based on the layer KKR Green function method, we have reproduced the Fe 3p angle-resolved soft x-ray photoemission spectra and analyzed the associated large magnetic dichroism effects for excitation with both linearly and circularly polarized light. Comparison between theory and experiment yields a spin-orbit splitting of 1.0 – 1.2 eV and an exchange splitting of 0.9 – 1.0 eV for Fe 3p. These values are 50 – 100 % larger than those hitherto obtained experimentally.

SPATIAL SEPARATION OF POLARIZATION COMPONENTS BY NONLINEAR BEAM RESHAPING IN A J=1 TO J=0 MEDIUM

1992 ◽  
Vol 01 (02) ◽  
pp. 393-420 ◽  
Author(s):  
R.J. BALLAGH ◽  
A.W. McCORD
Keyword(s):  
Optical Pumping ◽  
Polarized Light ◽  
Spatial Separation ◽  
Longitudinal Optical ◽  
Zero Field ◽  
Nonlinear Beam ◽  
Circularly Polarized Light ◽  
Polarized Beam ◽  
Light Beams ◽  
Elliptically Polarized

The diffractive reshaping that circularly polarized light beams undergo when coupled in a medium of homogenously broadened J=1→J=0 atoms is shown to be sensitively dependent on applied magnetic fields. In zero field, an elliptically polarized beam will retain its polarization everywhere in space, but a small longitudinal magnetic field can cause the beam to break up into spatially distinct regions of pure circular polarization. The beam behavior can be understood in terms of an encoding/diffraction sequence. An analytic solution for the atomic response function reveals the important roles played by transverse and longitudinal optical pumping.

scholarly journals Deep tuning of photo-thermoelectricity in topological surface states

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Shouyuan Huang ◽  
Ireneusz Miotkowski ◽  
Yong P. Chen ◽  
Xianfan Xu
Keyword(s):  
Surface State ◽  
Spin Injection ◽  
Three Dimensional ◽  
Polarized Light ◽  
Surface States ◽  
Linear Dispersion ◽  
Circularly Polarized Light ◽  
Spin Polarized ◽  
Topological Surface ◽  
Topological Surface State

Abstract Three-dimensional topological insulators have been demonstrated in recent years, which possess intriguing gapless, spin-polarized Dirac states with linear dispersion only on the surface. The spin polarization of the topological surface states is also locked to its momentum, which allows controlling motion of electrons using optical helicity, i.e., circularly polarized light. The electrical and thermal transport can also be significantly tuned by the helicity-control of surface state electrons. Here, we report studies of photo-thermoelectric effect of the topological surface states in Bi2Te2Se thin films with large tunability using varied gate voltages and optical helicity. The Seebeck coefficient can be altered by more than five times compared to the case without spin injection. This deep tuning is originated from the optical helicity-induced photocurrent which is shown to be enhanced, reduced, turned off, and even inverted due to the change of the accessed band structures by electrical gating. The helicity-selected topological surface state thus has a large effect on thermoelectric transport, demonstrating great opportunities for realizing helicity control of optoelectronic and thermal devices.

INFLUENCE OF OPTICAL PROPERTIES ON THE SPIN POLARIZATION OF Cu3P PHOTOELECTRONS

2002 ◽  
Vol 09 (02) ◽  
pp. 1173-1177 ◽  
Author(s):  
A. CHASSÉ ◽  
L. NIEBERGALL
Keyword(s):  
Optical Properties ◽  
Spin Polarization ◽  
Polarized Light ◽  
Polarization Vector ◽  
Transition Matrix Element ◽  
Macroscopic Theory ◽  
Circularly Polarized Light ◽  
Diffraction Patterns ◽  
Quantitative Changes ◽  
Optical Behavior

We have investigated the influence of optical properties of Cu(001) on the spin polarization in Cu 3p photoelectron diffraction patterns. The refraction and absorption of light have been taken into account in the calculation of the dipole transition matrix element. Therefore, a general polarization vector of light is defined within a macroscopic theory of electromagnetic fields. Results are shown and discussed for Cu 3p photoelectrons excited by linearly or circularly polarized light, respectively. It is shown that the optical behavior of crystals may cause a symmetry breaking in the angular dependence of the photoelectron intensity. Besides, there are strong quantitative changes in the related spin polarization of Cu 3p photoelectrons.

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