Doppler-shifted Acoustic Cyclotron Resonance Research Articles

Multiple doppleron‐phonon resonances in indium

Magnetic field dependences of absorption and phase velocity of circularly polarized ultrasonic waves were studied in super pure crystal of indium at the temperatures 1.28–4.2 K. Geometry of experiment corresponded to acoustic analogy of the Faraday effect. Multiple doppleron-phonon resonances were observed, as well as sharp peaks of Doppler-shifted acoustic cyclotron resonance and ultrasonic wave-field transport. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Doppler-Shifted Acoustic Cyclotron Resonance and Ultrasound Velocity in Deformed Tungsten

The effect of dislocations on the Doppler-shifted acoustic cyclotron resonance and the velocity of ultrasound are studied in pure tungsten single crystals. The measurements were made as the ultrasonic frequencies of 40 to 180 MHz with both longitudinal and transverse waves propagating along the [100] axis of the crystal. The relaxation rates and scattering cross-section of electrons were estimated in deformed samples as well as in undeformed ones. A comparison was carried out between the experimental temperature dependence of the modulus defect and theory.

Doppler-shifted acoustic cyclotron resonance in indium

The Fermi surface (FS) in In was investigated by the method of the Doppler-shifted cyclotron-resonance absorption of longitudinal sound (100-300 MHz) in magnetic fields from 0.5 to 50 kG. Extremal values of $|\frac{\ensuremath{\delta}{A}_{\ensuremath{\perp}}({k}_{B})}{\ensuremath{\delta}{k}_{B}}|$ were determined: ${A}_{\ensuremath{\perp}}({k}_{B})$ is the area of cross section of the FS perpendicular to $\stackrel{\ensuremath{\rightarrow}}{B}$ through the end of the vector ${k}_{B}\stackrel{^}{B}$. The sonic absorption was measured by the pulse-echo method. In has a fct structure. $\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}}$ was parallel to [001], [100], and [110] directions. $\stackrel{\ensuremath{\rightarrow}}{B}$ was varied in the (010), (001), and (110) planes. None of the observed absorption resonances appears to originate on the second-zone Fermi-hole surface. The most consistent interpretation of the Doppler-shifted acoustic cyclotron resonances (DSACR) is that they arise from the third-zone electron FS, including both the $\ensuremath{\alpha}$ and $\ensuremath{\beta}$ arms. In most, but not all, of the investigations of the FS in In by other methods, the $\ensuremath{\alpha}$ arms have not appeared. Local pseudopotential models for In have been based on the assumption that the $\ensuremath{\alpha}$ arms do not exist or are very small. While the existence of the $\ensuremath{\alpha}$ arms is not proven their existence is supported by this investigation. The amplitude of one series of DSACR oscillations was observed to decrease linearly with $T$.

Doppler-shifted acoustic cyclotron resonance in aluminum

Doppler-shifted cyclotron resonances (DSCR) have been observed with longitudinal and transverse acoustic waves propagating along the [001], [111], and [110] axes of pure aluminum crystals. One to three distinct series of resonance peaks have been observed in each field direction. The harmonic numbers of most DSCR series follow the selection rules for propagation along high symmetry axes. Except in the case ofB parallel to [110], the peak fields of the harmonics are inversely proportional to the harmonic numbers. Most of the DSCR series are identifiable with known DSCR zones on the Fermi surface, the area derivatives of which are then deduced. The area derivative data obtained are either more accurate or are complementary to those measured by helicon DSCR and magnetomorphic size-effect experiments. Values for Fermi surface area derivatives are compared with those calculated from two current models for the aluminum Fermi surface. Both the caps in [001] and [111] directions are shown to be free-electron-like.

Doppler-shifted acoustic cyclotron resonance in tungsten

Doppler-shifted cyclotron resonances have been observed acoustically in high purity tungsten single crystals. The resulting Fermi surface area derivatives agree generally with those obtained from magnetomorphic size effect experiments and with calculations based on an empirical model fitted to de Haas-van Alphen data. Certain non-central orbit zones of the latter model are modified to fit both sets of results. The resulting correction to the hole octahedron sheet is minimal, the modified electron jack has a more spherical shape, and the necks are slightly further away from the zone center. The dimensions of the re-parameterised model agree better with the results obtained from other Fermi surface measurements.

Doppler-shifted acoustic cyclotron resonance in tungsten

Doppler-shifted cyclotron resonances have been observed acoustically in high purity tungsten single crystals. The resulting Fermi surface area derivatives agree generally with those obtained from magnetomorphic size effect experiments and with calculations based on an empirical model fitted to de Haas-van Alphen data. Detailed discrepancies with the latter suggest corrections to the shapes of the non-central orbit zones on the Fermi surface model.

Observation of doppler-shifted acoustic cyclotron resonance: Voges, E., electronics letters (18 September 1969) (1834)

The Institute of Space and Astronautical Science (ISAS) has been engaged in the development study on the Air Turbo Ramjet (ATR) engine since 1986 in cooperation with the Ishikawajima Harima Heavy Industries Co. Ltd (IHI). The ATR is one of the most preferable candidates for the propulsion system of a future space plane. Our ATR engine is a combined cycle air breathing propulsion system which consists of the turbojet and the fan boosted ramjet using the liquid hydrogen as a fuel. This engine system was named “ATREX” after employing the expander cycle. The ATREX is energized by thermal energy extracted regeneratively in both the pre-cooler installed in the air intake and the heat exchanger in combustion chamber. The ATREX works in the flight condition from sea level static up to Mach 6 at 35 km altitude. The ATREX employs the tip turbine configuration for compactness of turbo machinery. We are assessing the feasibility of the ATREX system by the sea level static tests using the 14-scale model (ATREX-500) with a fan inlet diameter of 300 mm and overall length of 2120 mm. In 1990, the ATREX-500 engine was tested in a sea level static condition to verify the performance characteristics of the turbo machinery and the combustor. In September of 1991, the heat exchanger was installed in the combustion chamber and tested independently from the turbo system. In November of 1991, the heat exchanger was coupled with the turbo system and tested to verify the overall system of the ATREX. In this paper are presented the test results of the ATREX-500 engine tested in the sea level static condition.

Observation of Doppler-shifted acoustic cyclotron resonance in the microwave emission from InSb

Resonances near 1 and 2 kG have been observed in the low-field microwave emission from n-InSb at 77°K and 8.5 GHz with transverse magnetic field. These resonances can be interpreted as Doppler-shifted acoustic cyclotron resonance in good correspondence to earlier theoretical considerations.

A THEORETICAL EXPLANATION OF THE LOW-FIELD MICROWAVE EMISSION FROM InSb

A theory is presented for the microwave emission from n-InSb at 77°K in the presence of magnetic and low electric fields using Maxwellian electron velocity distribution and piezoelectric coupling between sound and plasma waves. The case of crossed fields is discussed in detail. Magnetoresistance effect and Doppler-shifted acoustic cyclotron resonance are the essential mechanisms which determine the magnetic field dependence of the microwave emission.

Microwave emission from n type InSb enhanced by Doppler-shifted acoustic cyclotron resonance

The microwave radiation emitted at 77 K from n InSb samples cut along the [110] direction, and subjected to a transverse magnetic field, showed maxima due to anticyclotron damping when the Doppler-shifted acoustic frequency was equal to the harmonics of the cyclotron frequency of the electrons.

Observation of Doppler-shifted acoustic cyclotron resonance in the frequency spectrum of the microwave emission from ntype InSb

The frequency spectra between 1.8 and 3GHz of the microwave radiation emitted from ntype InSb samples orientated along the [110] direction showed maxima in a transverse magnetic field, which can be attributed to Doppler-shifted acoustic cyclotron resonance.

Doppler-Shifted Acoustic Cyclotron Resonance in Gallium

The absorption of 260-MHz longitudinal sound waves in single crystals of gallium has been measured at 1.2\ifmmode^\circ\else\textdegree\fi{} K for propagation along the [100] axis. With the magnetic field in the (001) and (010) planes, sharp resonant peaks in the attenuation are observed over a large angular range centered on the propagation axis. Two series of absorption maxima, degenerate in the (010) plane, are attributed to a magnetoacoustic density-of-states resonance of seventh-band electron orbits for which the differential area $\frac{\mathrm{dA}}{d{k}_{z}}$ is an extremum. The average drift velocity and cyclotron effective mass obtained from the Doppler splitting are compared with corresponding parameters in the nearly free-electron approximation. Other resonances near the [100] axis are identified with seventh- and eighth-band orbits and are correlated with dc size-effect measurements. A Doppler-shifted open-orbit resonance for H\ifmmode\cdot\else\textperiodcentered\fi{}[010] associated with the sixth-band hole surface which permits open orbits in the [001] direction is described. The carrier drift along the sound propagation is obtained from the separation of corresponding subharmonic peaks for $\ifmmode\pm\else\textpm\fi{}n$.