Uniaxial strain dependence of the Fermi surface of tungsten

1977 ◽  
Vol 55 (4) ◽  
pp. 344-355 ◽  
Author(s):  
D. J. Stanley ◽  
J. M. Perz ◽  
M. J. G. Lee ◽  
R. Griessen
Keyword(s):  
Fermi Surface ◽  
Uniaxial Stress ◽  
Cross Sectional ◽  
Quantum Oscillations ◽  
Scattering Phase ◽  
Point Determination ◽  
Derivatives Of ◽  
Homogeneous Strain ◽  
Good Agreement

The derivatives of five representative cross sectional areas of the Fermi surface of tungsten with respect to uniaxial stress and strain along the cube axes, are determined experimentally from simultaneous measurements of quantum oscillations in magnetostriction and torque, and also in sound velocity and torque. The results are resolved into two components, the dependence on volume-conserving tetragonal shear, and the dependence on isotropic dilation. The tetragonal shear dependence is found to be in generally good agreement with the results of KKR calculations based on a fit to the unstrained Fermi surface. The isotropic dilation dependence agrees well with hydrostatic pressure measurements; from these results, the volume derivatives of the scattering phase shifts are deduced. This work is the first step towards a point-by-point determination of the distortion of the Fermi surface of tungsten in a lattice subjected to an arbitrary homogeneous strain.

Experimental determination of the dilational strain dependence of the Fermi surface of white tin

1980 ◽  
Vol 58 (4) ◽  
pp. 484-496 ◽  
Author(s):  
D. K. Mak ◽  
J. M. Perz
Keyword(s):  
Fermi Surface ◽  
Experimental Determination ◽  
Elastic Moduli ◽  
Hydrostatic Stress ◽  
Cross Sectional ◽  
Quantum Oscillations ◽  
Simultaneous Measurements ◽  
Landau Quantum ◽  
Derivatives Of

The derivatives with respect to uniaxial elongational strain of the areas of representative orbits on all sheets of the Fermi surface of tetragonal white tin have been deduced from simultaneous measurements of the Landau quantum oscillations in elastic moduli and in torque. Strain derivatives have been determined for most known extremal cross-sectional areas normal to the [100], [110], and [001] symmetry axes; the anisotropy of the strain derivatives of several area branches, having normal directions in the (010) and (001) planes, has also been studied. Uniaxial and hydrostatic stress derivatives deduced from the strain derivatives have been found to be generally consistent with values obtained by other means.

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.

Hydrostatic pressure and uniaxial stress derivatives of the Fermi surface of rhenium

1983 ◽  
Vol 61 (10) ◽  
pp. 1428-1433 ◽  
Author(s):  
J. R. Anderson ◽  
F. W. Holroyd ◽  
J. M. Perz ◽  
J. E. Schirber ◽  
I. M. Templeton
Keyword(s):  
Transition Temperature ◽  
Hydrostatic Pressure ◽  
Fermi Surface ◽  
Cross Sections ◽  
Solid Helium ◽  
Uniaxial Stress ◽  
Superconducting Transition ◽  
Cross Sectional ◽  
Effective Masses ◽  
Derivatives Of

Derivatives with respect to hydrostatic pressure of extremal cross-sectional areas normal to [Formula: see text] of all closed sheets of the Fermi surface of rhenium have been determined by both fluid–helium and solid–helium phase shift techniques. Precise values of de Haas–van Alphen frequencies and effective masses have also been measured for these cross sections. In addition, uniaxial stress derivatives of the zone seven cross sections have been deduced from quantum oseillations in magnetostriction and torque. Previously observed anomalies in the pressure dependence of the superconducting transition temperature are interpreted in terms of the present results.

Uniaxial stress and strain derivatives of the Fermi-surface necks in gold

1987 ◽  
Vol 65 (1) ◽  
pp. 13-15 ◽  
Author(s):  
H. Klimker ◽  
J. M. Perz ◽  
M. J. G. Lee
Keyword(s):  
Tensile Stress ◽  
Fermi Surface ◽  
Uniaxial Stress ◽  
Uniaxial Tensile ◽  
Direct Tension ◽  
Pressure Derivative ◽  
Cross Sectional ◽  
Uniaxial Tensile Stress ◽  
Compression Data ◽  
Derivatives Of

Simultaneous measurements of quantum oscillations in magnetostriction and torque in a single crystal of gold have been used to determine precise values for the derivatives of the cross-sectional area of the [111] neck of the Fermi surface with respect to uniaxial tensile stress along the [110] and [Formula: see text] directions. Independent estimates of the derivative with respect to uniaxial tensile stress along [111] of the neck area have been deduced from appropriate combinations of the [110] and [Formula: see text] stress derivatives with the established hydrostatic-pressure derivative. These estimates are in excellent agreement, giving ∂ lnA111/∂σ111 = (11.5 ± 0.3) × 10−12cm2∙dyn−1 (1 dyn = 10 μN). This result is significantly larger than the result of early direct-tension measurements in gold, suggesting that the latter suffered from systematic error. The present result is consistent with, and more precise than, earlier magnetostriction and direct uniaxial compression data. The angular shear derivative ∂ ln A/∂γ = 5.56 ± 0.17, deduced from the present data, is slightly larger than the theoretical value of 4.80 ± 0.20 obtained from a relativistic Korringa–Kohn–Rostoker phase-shift calculation based a rigid spherical muffin-tin pseudopotential.

The effect of hydrostatic pressure on the Fermi surface of white tin

1979 ◽  
Vol 57 (6) ◽  
pp. 884-889 ◽  
Author(s):  
J. M. Perz ◽  
I. M. Templeton
Keyword(s):  
Hydrostatic Pressure ◽  
Fermi Surface ◽  
Cross Sectional ◽  
Indirect Methods ◽  
Comprehensive Determination ◽  
Shift Technique ◽  
Direct And Indirect Methods ◽  
The Magnetic Field

The derivatives with respect to hydrostatic pressure of 12 extremal cross-sectional areas of the Fermi surface of tetragonal white (β) tin have been measured by the fluid helium de Haas van Alphen phase shift technique. The samples were carefully aligned in situ to have a crystal symmetry axis ([001], [100], or [110]) parallel to the magnetic field. The measured derivatives differ significantly from most values found previously by both direct and indirect methods; it is believed that the present work provides the first reliable comprehensive determination of these quantities. The present experiments also confirm the conclusions of magnetostriction experiments that there is a second orbit normal to [100] on the sixth zone surface not identified in earlier conventional de Haas van Alphen work, and that the third zone extremal areas normal to [001] are larger than previously accepted values determined in de Haas van Alphen studies.

Uniaxial strain derivatives of the Fermi surface of copper

1983 ◽  
Vol 61 (2) ◽  
pp. 177-187 ◽  
Author(s):  
D. W. Ruesink ◽  
J. M. Perz
Keyword(s):  
Experimental Study ◽  
Tensile Stress ◽  
Fermi Surface ◽  
Shear Strain ◽  
Cross Sections ◽  
The Other ◽  
Quantum Oscillations ◽  
Self Consistent ◽  
Torque Values ◽  
Derivatives Of

From a comprehensive experimental study of quantum oscillations in magnetostriction and torque, values have been deduced for all nonvanishing tetragonal and angular shear strain derivatives for the five principal extremal cross sections of the Fermi surface of copper, viz., the neck and belly normal to [111], the dogsbone normal to [110], and the rosette and belly normal to [001]. It is found that the neck is most sensitive to angular shear strain, whereas the bellies are most affected by uniform dilation. For the other orbits the magnitudes of shear and dilation derivatives are comparable.The results are self-consistent and agree with the experimental tensile stress results of Shoenberg and Watts. Earlier magnetostriction results for the neck obtained by Aron and by Slavin can be brought into agreement with the present data by recalculating the former using the now accepted value for the neck effective mass. The present experimental derivatives are in qualitative agreement with the theoretical values calculated by Lee, except for the tetragonal shear derivative of the [001] belly, for which the theoretical value is about 50% higher than the experimental one. This discrepancy is not fully understood.

scholarly journals TO A QUESTION OF DETERMINATION OF HYDRAULIC RADIUS OF A BACKFILL FLOW FOR THE EXCENTRATIVE PLACEMENT OF PIPES IN DRILLING BORE

2018 ◽  
pp. 197-209
Author(s):  
V. M. Moishyshyn ◽  
Y. S. Biletskii ◽  
V. V. Vryukalo ◽  
M. V. Seniushkovych
Keyword(s):  
Cross Section ◽  
Dimensionless Parameter ◽  
Internal Surface ◽  
Outer Radius ◽  
Hydraulic Radius ◽  
Cross Sectional ◽  
Internal Radius ◽  
First Time ◽  
Good Agreement

The processes of displacement of drilling clay backfill flow from the intertubular space formed by internal surface of external and external surfaces of inner tubes are considered. In case of eccentric placement of pipes it is proposed in the form of a cross-section of the flow of a backfill to take the area limited from the outside by the Pascal's snail, and from the inside - the outer surface of the inner pipe at the first time. The formulas for determining areas of the cross section of the flow and the stagnant zone, the perimeter and the hydraulic radius of the section ofthe flow for the eccentric placement of the pipes in the bore are proposed. The dimensionless parameter α is introduced as the ratio of the centripetal distance to difference between internal radius of outer pipe and outer radius of inner tube. It was found that with increasing of α cross-sectional area and their hydraulic radii are increasing, and the area of stagnant zones decreases according to parabolic laws.It is established that with the growth of α velocity of the backfill flow decreases according to parabolic laws and their values are in good agreement with the experimental data.

scholarly journals Absolute Pressure Dependence of the Second Ionization Level of EL2 in GaAs

1989 ◽  
Vol 163 ◽  
Author(s):  
D.E. Bliss ◽  
W. Walukiewicz ◽  
D.D. Nolte ◽  
E.E. Haller
Keyword(s):  
Pressure Dependence ◽  
Emission Rate ◽  
Uniaxial Stress ◽  
Absolute Pressure ◽  
Pressure Derivative ◽  
Effective Masses ◽  
The Difference ◽  
P Type ◽  
Derivatives Of ◽  
Good Agreement

AbstractWe report the results of DLTS experiments under uniaxial stress on the second ionization level of EL2(++/+) in p-type GaAs. We measured the shift in the hole emission rate as a function of stress applied in the [100] and [110] directions. By modeling the valence band with two independently displacing bands and appropriately derived effective masses, we obtain a small absolute hydrostatic pressure derivative for the defect, 39 ±15 meV GPa-1. The shear contribution is negligible. This result is very different than for the first ionization level, EL2(+/o) with a emission energy pressure derivative of 90 ±15 meV GPa-1. The difference can be accounted for by the pressure dependence of the electron capture barrier of EL2(+/o), 49 ±15meV GPa-1. The absolute pressure derivatives of the two levels are then comparable and in good agreement with simple theory for Ga site point defects.

scholarly journals Agreement and reproducibility of field and laboratory tests in the prediction of running speed in a 10-km race in amateur runners

Kinesiology ◽  
2020 ◽  
Vol 52 (2) ◽  
pp. 299-307
Author(s):  
Heitor Siqueira Ribeiro ◽  
Hugo de Luca Corrêa ◽  
Lívia Kelly Barbosa Lima ◽  
Maria Barroso Costa Filha ◽  
Severino Leão Albuquerque Neto ◽  
...  
Keyword(s):  
Low Cost ◽  
Time Trial ◽  
Cross Sectional Study ◽  
Running Speed ◽  
Cross Sectional ◽  
Preparation Period ◽  
Definition Of ◽  
Simulated Time ◽  
Good Agreement

Knowing running speed, particularly by means of easy-to-apply tests and low cost, is important for the definition of the race strategy and the most appropriate training throughout the preparation period. The aim was to compare the agreement and reproducibility of critical velocity (CV), anaerobic threshold (AT), and the simulated time trial on the track for the determination of the running speed in a 10-km race in amateur runners. A cross-sectional study was conducted with 34 runners of both genders aged 42.4±11.0 years. We measured their CV, assessed their body composition and AT. Participants performed also a simulated time trial on a 10-km running track and an official 10-km race. The delta of the comparisons and the standard error of estimate between the running velocities determined by the CV, AT, and the simulated time trial on the track ranged from 0.55 to -0.79 km/h and 0.14 to 0.59 km/h, respectively. Furthermore, CV and AT were compared to the 10-km running speed. Good agreement and reproducibility were observed between the velocities determined by the CV, AT, and the simulated time trial on the track with the real-time of a 10-km official race.

An experimental study of the Fermi surface of magnesium

1963 ◽  
Vol 276 (1365) ◽  
pp. 258-277 ◽  
Keyword(s):  
Magnetic Field ◽  
Fermi Surface ◽  
Field Method ◽  
Structure Calculation ◽  
Electron Trajectory ◽  
Band Structure Calculation ◽  
Cross Sectional ◽  
Field Orientation ◽  
Magnetic Field Orientation ◽  
Good Agreement

The de Haas-van Alphen effect in magnesium has been studied by the pulsed-field method developed by Shoenberg. Measurements were made of the periods of the oscillations as a function of magnetic field orientation, of the cyclotron masses at symmetry directions, and of the collision relaxation time. The absolute amplitudes were also compared with those calculated from the Lifshitz-Kosevieh expression using the observed parameters. The data on the extremal cross-sectional areas of the Fermi surface are com pared with the theoretical model deduced by Falicov from an OPW band structure calculation. Good agreement is found when magnetic breakdown is taken into account. The interpretation of some of the data requires the existence of a new kind of electron trajectory which is self-intersecting.

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