High Field Magnetoacoustic Investigation of the Fermi Surface of Tungsten

1973 ◽  
Vol 51 (1) ◽  
pp. 77-86 ◽  
Author(s):  
J. P. Kalejs ◽  
J. M. Perz
Keyword(s):  
Magnetic Field ◽  
Fermi Surface ◽  
Empirical Model ◽  
Cyclotron Resonance ◽  
High Field ◽  
Ultrasonic Waves ◽  
Quantum Oscillations ◽  
Resonance Data ◽  
The Magnetic Field ◽  
Longitudinal Ultrasonic Waves

We have measured the frequencies of quantum oscillations in the attenuation of 20 MHz longitudinal ultrasonic waves in tungsten in magnetic fields up to 109 kOe. Our results agree well with the de Haas–van Alphen (dHvA) data of Girvan, Gold, and Phillips (GGP). In addition, we see features predicted by the empirical model developed by GGP but not observed directly in the dHvA studies. Specifically, we find strong evidence of the continuation of the ω branch (GGP notation) for the magnetic field H in the [Formula: see text] plane right to the [110] direction; we also observe splitting of the ξ branch for field directions near [111], but not to the extent predicted by the model. From the temperature dependence of the amplitudes of the quantum oscillations, we have deduced cyclotron masses for some orbits; these agree well with GGP and cyclotron resonance data.

THE MILLIMETRE-WAVE MAGNETO-OPTICAL RESPONSE OF Sr2RuO4

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3238-3243
Author(s):  
A. ARDAVAN ◽  
E. RZEPNIEWSKI ◽  
R. S. EDWARDS ◽  
J. SINGLETON ◽  
Y. MAENO
Keyword(s):  
Magnetic Field ◽  
Fermi Surface ◽  
Effective Mass ◽  
Cyclotron Resonance ◽  
P Wave ◽  
Harmonic Series ◽  
Millimetre Wave ◽  
The Magnetic Field ◽  
Component Parallel ◽  
Absorption Mode

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.

Tipping effects in Azbel-Kaner cyclotron resonance

1967 ◽  
Vol 297 (1449) ◽  
pp. 205-229 ◽  
Keyword(s):  
Magnetic Field ◽  
Fermi Surface ◽  
Cyclotron Resonance ◽  
Skin Depth ◽  
Electron Model ◽  
Line Shapes ◽  
Parallel Polarization ◽  
Free Electron Model ◽  
Set Up ◽  
The Magnetic Field

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.

Dependence of the a-Si:H Defect Density of States on the Magnetic Field Profile of an Electron Cyclotron Resonance Microwave Plasma

1992 ◽  
Vol 258 ◽  
Author(s):  
F.S. Pool ◽  
J.M. Essick ◽  
Y.H. Shing ◽  
R.T. Mather
Keyword(s):  
Magnetic Field ◽  
Density Of States ◽  
Cyclotron Resonance ◽  
Electron Cyclotron Resonance ◽  
Microwave Plasma ◽  
Defect Density ◽  
Electron Cyclotron ◽  
Field Profile ◽  
Magnetic Field Profile ◽  
The Magnetic Field

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.

scholarly journals Квантовые осцилляции релаксации фотопроводимости в p-i-n-гетеродиодах GaAs/InAs/AlAs

2018 ◽  
Vol 52 (6) ◽  
pp. 591
Author(s):  
Ю.Н. Ханин ◽  
Е.Е. Вдовин
Keyword(s):  
Magnetic Field ◽  
Quantum Well ◽  
Oscillation Amplitude ◽  
Light Flux ◽  
Quantum Oscillations ◽  
Ballistic Motion ◽  
The Common ◽  
Relaxation Curves ◽  
Relaxation Characteristics ◽  
The Magnetic Field

AbstractThe photoconductivity and its relaxation characteristics in tunneling p – i – n GaAs/AlAs heterostructures under pulsed illumination is studied. Quantum oscillations in the photoconductivity are detected depending on the bias voltage with the period independent of the light wavelength, as well as an oscillating component of the relaxation curves caused by modulation of the recombination rate at the edge of a triangular quantum well in the undoped i layer, as in the case of photoconductivity oscillations. The common nature of oscillations of the steady-state photoconductivity and relaxation curves under pulsed illumination is directly confirmed by the lack of an oscillating component in both types of dependences of some studied p–i–n heterostructures. Simultaneous suppression of the observed oscillations of dependences of both types as the temperature increases to 80 K also confirms the proposed mechanism of their formation. The dependences of these oscillations on the magnetic field and light flux power are studied. Oscillation-amplitude suppression in a magnetic field of ~2 T perpendicular to the current is caused by the effect of the Lorentz force on the ballistic motion of carriers in the triangular-quantum-well region.

Experimental uniaxial stress and strain derivatives of the Fermi surface of rhenium

1980 ◽  
Vol 58 (8) ◽  
pp. 1191-1199 ◽  
Author(s):  
E. Fawcett ◽  
F. W. Holroyd ◽  
J. M. Perz
Keyword(s):  
Fermi Surface ◽  
Uniaxial Stress ◽  
Stress And Strain ◽  
Strong Anisotropy ◽  
Quantum Oscillations ◽  
Band Structure Calculations ◽  
Landau Quantum ◽  
Derivatives Of ◽  
Structure Calculations ◽  
The Magnetic Field

The derivatives of the areas of extremal orbits on all the small sheets of the Fermi surface of rhenium, with respect to stress and strain along the hexad axis, have been determined from simultaneous measurements of Landau quantum oscillations in magnetostriction and torque, and also in sound velocity and torque. Strong anisotropy is observed in the stress derivatives of orbits in zones five and six as the direction of the magnetic field defining the normal to the orbit is varied; the anisotropy is most pronounced for orbits which come close to the line of degeneracy AL on the hexagonal Brillouin zone face. The derivatives of the small void in zone eight are found to be very large; this is consistent with the results of band structure calculations which show that this feature of the Fermi surface is very sensitive to small changes in the Fermi energy. Cyclotron effective masses for a number of orbits on the void have also been measured.

Abstract 14497: Mri Effects on Pacemaker/ICD Within the Magnetic Field; An Intra-observer Variability Study

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Robert W Biederman ◽  
Loretta Gevenosky ◽  
Geetha Rayarao ◽  
RONALD WILLIAMS ◽  
Richard Lombardi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Field ◽  
Meaningful Use ◽  
Observer Variability ◽  
Intrinsic Variability ◽  
Mri Scan ◽  
Clinical Routine ◽  
The Impact ◽  
Variability Study ◽  
The Magnetic Field

Introduction: The evolution of pacemaker/ICD safety in the magnetic field has triggered considerable interest in more clinical routine use. However, many limitations to widespread adoption of this seemingly implausible idea just a few years ago remain: unresolved impact of the high magnetic field, RF amplitude and oscillatory forces on electronics with possible high field damage to capacitor, solenoid and microcircuitry. However, given recent vender refinements over the last 10 years, we hypothesized that the impact on such circuitry may be far less than expected. Method: Consecutive interrogation of 940 pts who underwent clinically indicated MRI were evaluated over 5 years. This cohort was comprised of neuro/neurosurgical (72%), orthopedic (11%) and cardiac (17%) cases. Routine interrogation was performed within 10 min of entry into the bore of a dedicated Cardiac MRI (GE, 1.5T, WI). As well, reinterrogation was performed within 10 min of departure MRI (average 21±12min). At the time of interrogation pre and post MRI, a separate, repeat interrogation was performed within 5 min of each other such that 2 sets of PM/ICD parameters were obtained pre and post MRI. Result: No complications to either pt or device occurred during the MRI comprising 564 PMs and 376 ICDs. A cardiologist was present guiding the interrogation, configuration, and reconfiguration of the PM/ICD as well was present for entire MRI. There were no significant differences in common clinical parameters. More importantly, there was no difference in any parameter when compared in any order pre to post MRI scan. See Table. Conclusion: Intrinsic variability and inherent changes triggered by MRI environments are clinically insignificant and statistically negligible thereby removing yet another of the last remaining fears and apprehensions for primary PM/ICD failure and destruction as we move towards a more uniform acceptance of this technology for clinically meaningful use, dissemination and acceptance.

scholarly journals Expansion of the high field-boosted superconductivity in UTe2 under pressure

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Sheng Ran ◽  
Shanta R. Saha ◽  
I-Lin Liu ◽  
David Graf ◽  
Johnpierre Paglione ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Field ◽  
Superconducting Phase ◽  
High Symmetry ◽  
First Order ◽  
Superconducting Phases ◽  
Quantum Phenomenon ◽  
Zero Resistance ◽  
Spin Triplet ◽  
The Magnetic Field

AbstractMagnetic field-induced superconductivity is a fascinating quantum phenomenon, whose origin is yet to be fully understood. The recently discovered spin-triplet superconductor, UTe2, exhibits two such superconducting phases, with the second one reentering in the magnetic field of 45 T and persisting up to 65 T. More surprisingly, in order to induce this superconducting phase, the magnetic field has to be applied in a special angle range, not along any high symmetry crystalline direction. Here we investigated the evolution of this high-field-induced superconducting phase under pressure. Two superconducting phases merge together under pressure, and the zero resistance persists up to 45 T, the field limit of the current study. We also reveal that the high-field-induced superconducting phase is completely decoupled from the first-order field-polarized phase transition, different from the previously known example of field-induced superconductivity in URhGe, indicating superconductivity boosted by a different paring mechanism.

scholarly journals Ultrasonic attenuation in lead

1963 ◽  
Vol 271 (1344) ◽  
pp. 88-104 ◽  
Keyword(s):  
Magnetic Field ◽  
Ultrasonic Attenuation ◽  
Absolute Magnitude ◽  
Transverse Magnetic ◽  
Ultrasonic Waves ◽  
Acoustic Oscillations ◽  
Connected Surface ◽  
Sample Orientation ◽  
Longitudinal Ultrasonic Waves

The absorption of longitudinal ultrasonic waves has been studied as a function of transverse magnetic field in pure single crystals of lead at 1.2 °K. The results were found to be generally consistent with the Fermi surface of lead suggested by Gold. In particular a detailed study of the magneto-acoustic oscillations, as a function of sample orientation and field direction, allowed the determination of some of the dimensions of the hole surface in the second Brillouin zone and revealed a number of new electronic orbits on the multiply-connected surface in the third zone. The absolute magnitude of the attenuation and its dependence on propagation direction and on magnetic field was studied and the results interpreted in terms of the general theory of ultrasonic absorption.

Magnetic Evidence for Reentrant Field-Induced Spin Density Waves

1989 ◽  
Vol 173 ◽  
Author(s):  
M. J. Naughton ◽  
R. V. Chamberlin ◽  
X. Yan ◽  
P. M. Chaikin ◽  
L. Y. Chiang
Keyword(s):  
Magnetic Field ◽  
Spin Density ◽  
High Field ◽  
Density Wave ◽  
Spin Density Wave ◽  
Metallic Phase ◽  
Wave State ◽  
T Phase ◽  
Resistance Data ◽  
The Magnetic Field

ABSTRACTHigh magnetic field (to 31T) d.c. magnetization measurements on the quasi-one dimensional organic conductor (TMTSF) 2ClO4 yield thermodynamic evidence for the reentrance of a metallic phase from the magnetic field-induced spin density wave state. The H-T phase diagram developed previously from magnetotransport measurements is reproduced from 8 to 26 tesla. The reentrance occurs as a sharp collapse of M(H) to (near) zero magnetization in the high field metal phase. For fields above 27 tesla, deHaas-van Alphen-like oscillations appear, similar to earlier resistance data, as well as other features possibly signifying multiple transitions in the very high field regime.

Cyclotron resonance in the extreme anomalous relaxation region

1964 ◽  
Vol 278 (1373) ◽  
pp. 256-273 ◽  
Keyword(s):  
Magnetic Field ◽  
Electron Scattering ◽  
Cyclotron Resonance ◽  
Surface Resistance ◽  
Electron Gas ◽  
Degenerate Semiconductors ◽  
Line Shapes ◽  
Infra Red ◽  
Anomalous Relaxation ◽  
The Magnetic Field

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.

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