Cyclotron resonance in the extreme anomalous relaxation region

A reformulation of the theory of cyclotron resonance in metals as a variational problem is combined with the exact solution of the Boltzmann equation and used to calculate the surface resistance of an isotropic electron gas, in the extremeanom alous relaxation region, as a function of an applied magnetic field parallel to the surface of the medium . The line shapes obtained depend strongly on the diffuse or specular nature of the electron scattering a t the surface and also on the longitudinal or transverse orientation of the magnetic field relative to the current. The effect should be observable in degenerate semiconductors and semimetals a t infra-red frequencies.

Calculations of Azbel-Kaner line shapes when the magnetic field is tipped out of the surface have been carried out in a number of cases for both the free electron model and an arbitrary Fermi surface with mass spread. For small angles of tip the results substantiate the Doppler shift theory advanced by Koch, Stradling & Kip and provide a consistent explanation of the observed peak shifts or splitting in all cases. Arguments are presented that at larger tip angles the overall absorption will decrease with increasing field, and the original resonance may become inverted, owing to the removal of non-stationary electrons from the skin depth. At large tip angles (5° or so) inverted and doubled resonances observed with parallel polarization are shown to arise from ‘field splashes’ set up by drifting electrons from the limiting points, regardless of the nature of the Fermi surface. Apparently normal resonances observed at very large tip angles are shown to arise from so-called ‘cylinder sections’ where d A /dk 2 H = 0 and v D = 0, A and v D being the area of the orbit in k space and the drift velocity respectively.


1992 ◽  
Vol 258 ◽  
Author(s):  
F.S. Pool ◽  
J.M. Essick ◽  
Y.H. Shing ◽  
R.T. Mather

ABSTRACTThe magnetic field profile of an electron cyclotron resonance (ECR) microwave plasma was systematically altered to determine subsequent effects on a-Si:H film quality. Films of a-Si:H were deposited at pressures of 0.7 mTorr and 5 mTorr with a H2/SiH4 ratio of approximately three. The mobility gap density of states ND, deposition rate and light to dark conductivity were determined for the a-Si:H films. This data was correlated to the magnetic field profile of the plasma, which was characterized by Langmuir probe measurements of the ion current density. By variation of the magnetic field profile ND could be altered by more than an order of magnitude, from 1×1016 to 1×1017 at 0.7 mTorr and 1×1016 to 5×1017 at 5 mTorr. Two deposition regimes were found to occur for the conditions of this study. Highly divergent magnetic fields resulted in poor quality a-Si:H, while for magnetic field profiles defining a more highly confined plasma, the a-Si:H was of device quality and relatively independent of the magnetic field configuration.


Author(s):  
M S Munoz ◽  
G A Wade ◽  
Y Nazé ◽  
J Puls ◽  
S Bagnulo ◽  
...  

Abstract In this paper, we investigate the photometric variability of magnetic O-type stars. Such stars possess oblique, predominantly dipolar magnetic fields that confine their winds roughly axisymmetrically about the magnetic equator, thus forming a magnetosphere. We interpret their photometric variability as phase-dependent magnetospheric occultations. For massive star winds dominated by electron scattering opacity in the optical and NIR, we can compute synthetic light curves from simply knowing the magnetosphere’s mass density distribution. We exploit the newly-developed Analytical Dynamical Magnetosphere model (ADM) in order to obtain the predicted circumstellar density structures of magnetic O-type stars. The simplicity in our light curve synthesis model allows us to readily conduct a parameter space study. For validation purposes, we first apply our algorithm to HD 191612, the prototypical Of?p star. Next, we attempt to model the photometric variability of the Of?p-type stars identified in the Magellanic Clouds using OGLE photometry. We evaluate the compatibility of the ADM predictions with the observed photometric variations, and discuss the magnetic field properties that are implied by our modelling.


2002 ◽  
Vol 16 (20n22) ◽  
pp. 3238-3243
Author(s):  
A. ARDAVAN ◽  
E. RZEPNIEWSKI ◽  
R. S. EDWARDS ◽  
J. SINGLETON ◽  
Y. MAENO

We report a study of the angle-dependent millimetre-wave magnetoconductivity of the p-wave triplet-paired perovskite superconductor Sr 2 RuO 4. We find two harmonic series. We assign the first to interlayer cyclotron resonance of the β-Fermi surface and its harmonics, yielding a cyclotron effective mass of [Formula: see text]. We assign the second series, which contains only odd harmonics, to cyclotron resonance of the γ-Fermi surface, yielding a cyclotron effective mass of [Formula: see text]. In addition, we find a very strong absorption mode in the presence of a magnetic field component parallel to the quasi-two-dimensional (Q2D) planes of the sample. Its dependence on the orientation of the magnetic field cannot be described in the context of conventional Q2D cyclotron resonance, and the origin of this mode is not yet clear.


2007 ◽  
Vol 21 (28) ◽  
pp. 1885-1893 ◽  
Author(s):  
L. REN

For a two-dimensional electron gas with equal Rashba and Dresselhaus spin-orbit coupling strength (ReD model), and the Dresselhaus [110] model, the influence of an external magnetic field on the lifetime of the Spin Helix (SH) has been considered. A perpendicular magnetic field has no influence on the lifetime of the SH for the Dresselhaus [110] model, independent of the strength of the magnetic field. But for the ReD model, when the magnetic field is weak, and we only take the linear term of the magnetic field B into account, the conclusion is still so. In addition, if the external magnetic field is in-plane with a suitable angle between the x and y component, the lifetime of the SH will also be infinite.


2020 ◽  
Vol 90 (6) ◽  
pp. 1022
Author(s):  
В.Н. Пашенцев ◽  
М.В. Пашенцева

Pashentsev V.N.1, Pashentseva M.V.2 1 National Research Nuclear University MEPhI 115409 Moscow, Russia 2 Lomonosov Moscow State University 119991 Moscow, Russia e-mail: [email protected] A method for accelerating electrons in a smooth cylindrical waveguide placed in the magnetic field of a solenoid is proposed. The motion of electrons in the waveguide occurs along a spiral trajectory shifted from the center of the waveguide. Electrons are accelerated at the cyclotron resonance frequency by the E01 or E02 waves in the direction of the waveguide axis. It is shown that the acceleration occurs as a result of synchronous rotation of particles in the cross section of the waveguide and the movement of the wave along the waveguide axis. When the electric field is maximum and has an decelerating direction, the electrons are in the center of the waveguide. Through the half-period, the direction of the electric field in the center will be braking, so under the influence of the magnetic field, the electrons rotate to the wall of the waveguide in the region of a smaller value of the decelerating electric field. It is shown that during the period of rotation of electrons the total effect of interaction of electrons with a wave is accelerating. The parameters of the accelerator for the energy of 10 MeV are estimated.


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