scholarly journals Magnetic control of polariton spin transport

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
D. Caputo ◽  
E. S. Sedov ◽  
D. Ballarini ◽  
M. M. Glazov ◽  
A. V. Kavokin ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Spin Transport ◽  
Beat Frequency ◽  
Magnetic Control ◽  
Polarization Pattern ◽  
Spin Degree ◽  
Full Control ◽  
Planar Microcavity ◽  
The Magnetic Field ◽  
Photon Coupling

AbstractPolaritons are hybrid light–matter quasiparticles arising from the strong coupling of excitons and photons. Owing to the spin degree-of-freedom, polaritons form spinor fluids able to propagate in the cavity plane over long distances with promising properties for spintronics applications. Here we demonstrate experimentally the full control of the polarization dynamics of a propagating exciton–polariton condensate in a planar microcavity by using a magnetic field applied in the Voigt geometry. We show the change of the spin-beat frequency, the suppression of the optical spin Hall effect, and the rotation of the polarization pattern by the magnetic field. The observed effects are theoretically reproduced by a phenomenological model based on microscopic consideration of exciton–photon coupling in a microcavity accounting for the magneto-induced mixing of exciton–polariton and dark, spin-forbidden exciton states.

scholarly journals The Hα Emission of the PMS Star Serpens/SVS 2

1990 ◽  
Vol 140 ◽  
pp. 318-318
Author(s):  
A.I. Gomez De Castro
Keyword(s):  
Magnetic Field ◽  
Star Formation ◽  
Major Axis ◽  
Mass Star ◽  
Polarization Pattern ◽  
Bipolar Structure ◽  
Dust Disk ◽  
Hα Emission ◽  
Low Mass ◽  
The Magnetic Field

Serpens is a region of low mass star formation where the magnetic field seems to play a fundamental role. The major axis of the Serpens outflows are aligned with the magnetic field. The most outstanding object in the region is the Serpens Reflection Nebula, SRN. This is characterized by a rather complex bipolar structure with several knots of gas and dust embedded in both nebular lobes. The western lobe is directed out of the cloud toward the observer. The SRN is illuminated by the PMS star Serpens/SVS 2. The star is surrounded by a dust disk; the polarization pattern of the disk can be interpreted as produced by dust grains aligned by the magnetic field frozen-in with the disk.

scholarly journals Taming the Janssen effect

2021 ◽  
Vol 249 ◽  
pp. 08004
Author(s):  
Louison Thorens ◽  
Knut Jørgen Måløy ◽  
Mickaël Bourgoin ◽  
Stéphane Santucci
Keyword(s):  
Magnetic Field ◽  
Radial Force ◽  
Dipole Interactions ◽  
Full Control ◽  
Grain Packing ◽  
Experimental Findings ◽  
The Magnetic Field ◽  
Measured Mass ◽  
Granular Column ◽  
True Mass

We investigate both experimentally and theoretically the apparent mass of a ferromagnetic granular assembly filling a cylindrical container and submitted to a magnetic field B, aligned vertically along the silo. We show that the mass of the ferromagnetic granular column depends strongly on the applied magnetic field. Notably, our measurements deviate strongly from the exponential saturation of the measured mass as a function of the true mass of the grain packing, as predicted by Janssen [H.A. Janssen, Vereins Eutscher Ingenieure Zeitschrift, 1045 (1895)]. In particular, the measured mass of tall columns decreases systematically as the amplitude of the magnetic field increases. We rationalize our experimental findings by considering the induced magnetic dipole-dipole interactions within the whole packing. We show the emergence of a global magnetic radial force along the walls of the silos, fully determined by the external magnetic field. The resulting tunable frictional interactions allows a full control of the effective mass of the ferromagnetic granular column.

REEXAMINATION OF SPIN TRANSPORT THROUGH A DOUBLE-δ MAGNETIC BARRIER WITH SPIN-ORBIT INTERACTIONS

2009 ◽  
Vol 23 (30) ◽  
pp. 3631-3642
Author(s):  
CAIHUA BI ◽  
FENG ZHAI
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Spin Polarization ◽  
Energy Region ◽  
Spin Transport ◽  
Inhomogeneous Magnetic Field ◽  
Pure Spin ◽  
Spin Orbit ◽  
Spin Orbit Interactions ◽  
The Magnetic Field

We revisit the properties of spin transport through a semiconductor 2DEG system subjected to the modulation of both a ferromagnetic metal (FM) stripe on top and the Rashba and Dresselhaus spin-orbit interactions (SOIs). The FM stripe has a magnetization along the transporting direction and generates an inhomogeneous magnetic field in the 2DEG plane which is taken as a double-δ shape. It is found that the spin polarization of this system generated from a spin-unpolarized injection can be remarkable only within a low Fermi energy region and is not more than 30% for the parameters available in current experiments. In this energy region, both the magnitude and the orientation of the spin polarization can be tuned by the Rashba strength, the Dresselhaus strength, and the magnetic field strength. The magnetization reversal of the FM stripe cannot result in a change of the conductance, but can rotate the orientation of the spin polarization. The results are in contrast to those in [ J. Phys.: Condens. Matter15 (2003) L31] where a pure spin state for incident electrons is artificially assumed.

Magnon photon coupling for magnetization antiparallel to the magnetic field

2021 ◽  
Vol 103 (10) ◽  
Author(s):  
Y. Xiao ◽  
X. H. Yan ◽  
L. H. Bai ◽  
H. Guo ◽  
C. M. Hu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
The Magnetic Field ◽  
Photon Coupling

scholarly journals Beat wave cyclotron heating of rippled density plasma

2018 ◽  
Vol 36 (4) ◽  
pp. 465-469 ◽  
Author(s):  
Pushplata ◽  
A. Vijay
Keyword(s):  
Magnetic Field ◽  
Large Amplitude ◽  
Ponderomotive Force ◽  
Beat Frequency ◽  
Magnetized Plasma ◽  
Larmor Radius ◽  
Finite Larmor Radius ◽  
Wave Heating ◽  
The Magnetic Field ◽  
Density Plasma

AbstractLaser beat wave heating of magnetized plasma via electron cyclotron damping is proposed and analyzed. A plasma density ripple is presumed to exist across the magnetic field. Two collinear lasers propagating along the magnetic field exert a beat frequency ponderomotive force on electrons, driving a large amplitude Bernstein quasi-mode which suffers cyclotron damping on electrons. Finite Larmor radius effects play an important role in the heating. Electron temperature initially rises linearly with time. As the temperature rises cyclotron damping becomes stronger and temperature rises rapidly. The process, however, requires ripple wavelength shorter than the wavelength of the beat wave.

MIRROR BIREFRINGENCE IN A FABRY-PEROT CAVITY AND THE DETECTION OF VACUUM BIREFRINGENCE IN A MAGNETIC FIELD

1995 ◽  
Vol 10 (28) ◽  
pp. 2125-2134 ◽  
Author(s):  
T.C.P. CHUI ◽  
M. SHAO ◽  
D. REDDING ◽  
Y. GURSEL ◽  
A. BODEN
Keyword(s):  
Magnetic Field ◽  
Quantum Electrodynamics ◽  
State Of The Art ◽  
Beat Frequency ◽  
Polarization Rotation ◽  
High Susceptibility ◽  
First Order ◽  
Fabry Perot ◽  
High Finesse ◽  
The Magnetic Field

Quantum electrodynamics (QED) theory predicts that vacuum under the influence of a strong magnetic field is birefringence. Recently, several groups have proposed to used a high finesse Fabry—Perot cavity to increase the average path length of the light in the magnetic field. This together with the state-of-the-art dipole magnets, should bring the effect within reach of observation. However, the mirrors used in the FP are known to have intrinsic birefringence which is of orders of magnitude larger than the birefringence of the vacuum. In this letter, we analyze the effect of uncontrollable variations of mirror birefringence on two recently proposed optical schemes. The first scheme,1 which we called the frequency scheme, is based on measurement of the beat frequency of two orthogonal polarized laser beams in the cavity. We show that mirror birefringence contributes to the detection uncertainties in first order, resulting in a high susceptibility to variations of its value. In the second scheme, which we called the polarization scheme, laser polarized at 45° relative to the B-field is injected into the cavity. The ellipticity and polarization rotation of the light exiting the cavity is measured.2 Under this scheme, mirror birefringence contributes as a correction of the QED effect, greatly reducing its sensitivity to the undesirable changes.

scholarly journals Magnetic control of the plasma flows in laser targets

1994 ◽  
Vol 12 (3) ◽  
pp. 371-377 ◽  
Author(s):  
S.Yu. Gus'kov ◽  
V.B. Rozanov ◽  
T. Pisarczyk
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Laser Beam ◽  
Plasma Flow ◽  
Laser Beams ◽  
Magnetic Control ◽  
Plasma Flows ◽  
The Magnetic Field ◽  
Magnetic Field Transverse

The idea of controlling the plasma flows in laser targets by action of a strong external magnetic field (H ≥ 1 MG) is presented. The magnetic control of plasma flows for the keeping of a transparency of entrance holes of indirect-compression targets and other type targets operating at an introduction of the laser beams into the interior of the target is suggested. It is shown that the magnetic field, transverse versus the direction of the propagation of the plasma flow with an intensity of 2–4 MG, causes a decrease (1.5–3 times) of the closing speed of holes for the laser beam introduction into the hohlraum target.

Observing the galactic magnetic field

1967 ◽  
Vol 31 ◽  
pp. 375-380
Author(s):  
H. C. van de Hulst
Keyword(s):  
Magnetic Field ◽  
Fair Agreement ◽  
Solar Neighbourhood ◽  
Galactic Magnetic Field ◽  
The Magnetic Field

Various methods of observing the galactic magnetic field are reviewed, and their results summarized. There is fair agreement about the direction of the magnetic field in the solar neighbourhood:l= 50° to 80°; the strength of the field in the disk is of the order of 10-5gauss.

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

2000 ◽  
Vol 179 ◽  
pp. 263-264
Author(s):  
K. Sundara Raman ◽  
K. B. Ramesh ◽  
R. Selvendran ◽  
P. S. M. Aleem ◽  
K. M. Hiremath
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Ultra Violet ◽  
Active Regions ◽  
Morphological Properties ◽  
Energy Storage And Conversion ◽  
The Sun ◽  
X Rays ◽  
The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust & Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust & Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

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