Submillimetre cyclotron resonance measurement of the effective masses of the holes in p-type GaP

The effective mass ratios of the heavy and light holes at the band edge of p-type gallium phosphide have been determined by submillimetre cyclotron resonance at 77 K. The values obtained are 0.54 ± 0.05 and 0.16 ± 0.02 respectively. A comparison is made with k.p calculations of these quantities.     

Microwave cyclotron resonance of hot electrons in p-type GaSb

A microwave photocreated cyclotron resonance signal is observed in p-type GaSb in the temperature range 1–30 K. Circular polarization and other measurements identify the carriers as electrons in the (000) conduction band. The problem of a surface effect on the measured peak position, reported for the first time is avoided by bulk carrier creation. An exponential loss of signal intensity at 27 K is explained by the theory of background plasma effects. The measured ωτ of 1·5–4 yields an electron collision time of τ ～ 10^?11 sec. The scattering mechanism at liquid helium temperatures is identified as being partly due to neutral defect acceptor scattering of hot electrons, with an unidentified residual scattering process. The electron polaron effective mass is measured to be (m *(polaron)/m₀) = 0·0412 ± 0·0012 for hot electrons with an average energy of ～ 14 MeV and is isotropic within 1 per cent. When corrections for conduction-band non-parabolicity and hot polaron effects are applied, the band-edge free electron mass is calculated to be (m₀*(free)/m₀) = 0·0396 ± 0·0021 (±5·2 per cent).     

Shift in cyclotron resonance of electrons on liquid helium surfaces

We calculate the increase in cyclotron resonance frequency for electrons trapped within dimples on a liquid helium surface, when a vertical electric field is applied in addition to the strong vertical magnetic field.     

On the temperature dependent cyclotron resonance lineshape of inversion-layer electrons in Si

Unlike the electron-impurity interaction, the electron-acoustic phonon interaction generates a temperature-dependent cyclotron resonance lineshape. The difference is due to the temperature-dependent phonon distribution and the quasi-inelastic nature of the electron-phonon scattering. Calculations based on the proper connected diagram expansion are in qualitative agreement with experiments on inversion-layer electrons in Si in the temperature range 8–65 K.     

Theory of cyclotron resonance width for electrons inelastically scattered by phonons

The cyclotron resonance width for a semiconductor under extreme high fields is calculated with the assumptions that electrons are scattered by acoustic phonons inelastically. The numerical results are in very good agreement with the recent experiments on Ge by Miura et al. (T ～ 300 K, B ～ 97 tesla). The energy-dependent widths arising from the relaxation processes with absorption and emission of a phonon show quite distinctive behaviors at low electron energies. At extreme low temperatures when few phonons are present, the width arising from the zero-point motion of the lattice is finite but very small. The charged-impurity scattering with the density as low as 10¹² cm^?3 numerically dominate the width due to the electron-phonon interaction below 10 K. The present theory supplements the previous work by Suzuki et al. where the elastic-scattering and high-temperature approximation were used.     

Effect of the spin-orbit interaction on the cyclotron resonance of two-dimensional electrons

In the cyclotron resonance (CR) spectra of two-dimensional (2D) electrons in InAs quantum wells, the CR line splitting is observed. The splitting is found to be an oscillating function of magnetic field. The oscillations do not correlate with the filling factor. The experimental results are interpreted in terms of the spin-orbit splitting in the presence of a built-in electric field appearing due to the asymmetry of the quantum-well potential. From the splitting of the CR line, the spin-orbit coupling constant α_so is determined. The resulting value agrees well with the value obtained for the same sample from the Shubnikov-de Haas oscillations. The role of the resonance interaction of charge carriers in the well with the interface donor states is discussed.     

Theory of cyclotron resonance halfwidth for electrons scattered by impurities and phonons

A general theory of the cyclotron resonance halfwidth for electrons scattered by impurities and phonons is developed on the basis of the proper connected diagram expansion of the current-correlation-function formula for the dynamic conductivity. The theory is applied to the cases of Ge samples at extremely high magnetic fields and different temperatures. The usual form of Matthiessen's rule Γ = Γ₁ + Γ₂ + …, where Γ and Γ_j are the total and component energy-dependent resonance widths, is valid only if the component widths Γ_j computed separately for each cause of scattering depend linearly on the densities of scatterers. The resonance width Γ_I due to the charged impurities at very low electron densities ($\text{\$}\text{?}$10¹² cm^?3) and at very low temperatures is known to vary in proportion to the square-root of the impurity density. Large deviations from the Matthiessen's rule occur in such a case. The theory is in good quantitative agreement with currently available experimental data. In order to test the generalized form of Matthiessen's rule, however, the high-field resonance experiments around 15 K is desirable where both phonon and impurity scatterings contribute in a comparable manner.     

Parametric generation of low-frequency waves by plasma electrons accelerated under electron cyclotron resonance conditions

It has been shown experimentally that the diamagnetic effect appearing when electrons of a magnetized plasma in the antenna near field are accelerated under electron cyclotron resonance conditions can be used to generate low-frequency waves. The amplitude modulation of a signal supplied to the antenna is accompanied by the modulation of the diamagnetic effect and leads to the emission of waves at the modulation frequency to the surrounding plasma. In this process, the extended plasma region containing accelerated electrons serves as a parametric bodiless antenna. The results of the model laboratory experiments make it possible to propose a method for the parametric generation of low-frequency whistler waves in the Earth’s ionosphere by a powerful amplitude-modulated signal supplied to the satellite-borne antenna.     

Hole mass measurement in p-type InP and GaP by submillimetre cyclotron resonance in pulsed magnetic fields

The first observation of cyclotron resonance in p-type InP is reported. The holes were thermally excited at 110 K and the resonance was observed at 337μm wavelength (HCN laser) using a pulsed magnetic field of 0–350 kG. The effective masses of the light and heavy holes in the 〈111〉 direction were found to be $\text{m}{}^1{}_{\mathrm{<mtext>L</mtext>}}\text{= 0.12 ± 0.01 m}{}_0$, and in the 〈100〉 direction $\text{m}{}^1{}_{\mathrm{<mtext>L</mtext>}}\text{= 0.12 ± 0.01 m}{}_0$, $\text{m}{}^1{}_{\mathrm{<mtext>H</mtext>}}\text{= 0.56 ± 0.02 m}{}_0$. We obtain an estimate of the Dresselhaus parameters A = ?5.04, |B| = 3.12, C² = 6.57. We also report the effective masses for p-type GaP in the 〈111〉 direction as $\text{m}{}^1{}_{\mathrm{<mtext>L</mtext>}}\text{= 0.18 ± 0.02 m}{}_0$, $\text{m}{}^1{}_{\mathrm{<mtext>H</mtext>}}\text{= 0.56 ± 0.04 m}{}_0$.     

Five-level k · p model for conduction electrons in GaAs. Description of cyclotron resonance experiments

Five-level k·p model for the conduction electrons in GaAs in the presence of a quantising magnetic field is developed and used to describe spin splittings of the cyclotron resonance and the donor-shifted cyclotron resonance peaks, observed in this material up to fields of 22.5 T. It is shown that the spin splittings are insensitive to polaron effects and that their values can be very well described by the model.Required band parameters correctly account for the rate of electron spin relaxation in GaAs due to inversion asymmetry, as determined by other authors.     

Energies of electrons bound to nitrogen pairs in GaP

The binding energies of electrons bound to nitrogen pairs in GaP are evaluated by use of the effective mass theory with a suitable model potential. The variational procedure yields (i) satisfactory agreement with previous experimental values for nitrogen pairs and (ii) no bound state for the isolated nitrogen atom. Our results suggest the electron to be bound in a potential with strain-like contributions which approaches earlier ideas of Allen.     

A note on the negative absorption of electromagnetic waves at the cyclotron resonance of plasma electrons

The quantum interpretation of the negative absorption of electromagnetic waves at the cyclotron resonance of plasma is given, and the conditions under which the negative absorption takes placs are examined.     

Far-infrared cyclotron resonance in n-Ge

Cyclotron resonance has been performed on the conduction band of germanium using a cyanide laser at 891 GHz and a superconducting magnet of up to 110 kG. This is 2.5 times higher in frequency and 10 times higher in field than previous cyclotron resonance measurements reported for n-Ge. The effective masses do not change from their calues at lower frequencies and fields, but the scattering frequencies are 1.5 to 5 times larger. A new scattering mechansm is suggested to explain the increased scattering.     

Surface cyclotron resonance in InSb

We have studied cyclotron resonance of electrons in an inversion layer on the surface of p-type InSb. With increasing surface charge density n_s a number of distinct resonance peaks are found to appear. These are attributed to cyclotron resonance in different electric subbands. The various cyclotron masses are found to increase with n_s and with the frequency of the far-infrared laser source.     

Bistable cyclotron resonance in semiconductors

We consider the cyclotron resonance in a semiconductor which has a band with a relativistic energy-momentum dispersion and show that, when subject to quasi-resonant radiation, the energy of a free carrier in this band and the relative potential drop between the two surfaces of the semiconductor facing the radiation exhibit bistability under classical single electron approximation.     

Amplitude characteristic of cyclotron resonance

The motion of a charged particle under the combined action of a magnetostatic field and a circularly polarized electromagnetic wave of phase velocity u higher than c, the wave being aligned with the field, is studied theoretically. A nonlinear resonance curve is found. Certain integrals of motion are derived.     

Intra-Landau-level cyclotron resonance in bilayer graphene

Interaction driven integer quantum-Hall effects are anticipated in graphene bilayers because of the near degeneracy of the eight Landau levels which appear near the neutral system Fermi level. We predict that an intra-Landau-level cyclotron resonance signal will appear at some odd-integer filling factors, accompanied by collective modes which are nearly gapless and have approximate k3/2 dispersion. We speculate on the possibility of unusual localization physics associated with these modes.