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 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.

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.

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.

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.

scholarly journals Distinct superconducting properties and hydrostatic pressure effects in 2D α- and β-Mo2C crystal sheets

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Yunjie Fan ◽  
Chuan Xu ◽  
Xiang Liu ◽  
Chao Ma ◽  
Yuewei Yin ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Hydrostatic Pressure ◽  
Electronic Properties ◽  
Superconducting Transition Temperature ◽  
Important Influence ◽  
Pressure Effects ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
Disordered Carbon

Abstract Recently, 2D Mo2C, a new member of the MXene family, has attracted much attention due to the exotic superconducting properties discovered in 2D α-Mo2C. Here, not only 2D α-Mo2C but also 2D β-Mo2C crystal sheets with distinct disordered carbon distributions were successfully grown. 2D β-Mo2C shows a much stronger superconductivity than 2D α-Mo2C, and their superconductivities have different hydrostatic pressure responses. The superconducting transition temperature Tc of 2D α-Mo2C shows a dome-shaped profile under pressure, implying the existence of two competing effects arising from phononic and electronic properties, while for 2D β-Mo2C, Tc decreases monotonically with increasing pressure, possibly due to phonon stiffening. These results indicate that the electronic properties have a more important influence on the superconductivity in 2D α-Mo2C compared to 2D β-Mo2C. The ordered and disordered carbon distributions in 2D α-Mo2C and β-Mo2C, respectively, may be the underlying origin for their different electronic and superconducting properties.

Superconductivity and Intralayer Structure in Potassium Amalgam-Gic

1982 ◽  
Vol 20 ◽  
Author(s):  
G. Timp ◽  
B.S. Elman ◽  
M.S. Dresselhaus ◽  
P. Tedrow
Keyword(s):  
Transition Temperature ◽  
Fermi Surface ◽  
Electronic Properties ◽  
Raman Spectra ◽  
Basal Plane ◽  
High Frequency ◽  
Superconducting Transition Temperature ◽  
Superconducting Transition ◽  
Lattice Fringe ◽  
Structural Lattice

ABSTRACTWe report on the structural, lattice and electronic properties of stage 1,2,3 potassium-amalgam GIG and the relation of these properties to the observed superconducting transition temperature. The ultramicrostructure of the intercalant domains is investigated using lattice fringe imaging. Our observation of macroscopic (√3×√3),(2×2) and (√3×2) domains is consistent with the basal plane zonefolded phenomena observed in the Raman spectra. Shubnikovde Haas measurements of the Fermi surface show high frequency (>1000 T) oscillations in stage 2, identified with the intercalant band.

scholarly journals Elastic Behaviour of Terbium Metaphosphate Glasses Under High Pressures

1994 ◽  
Vol 47 (6) ◽  
pp. 795 ◽  
Author(s):  
HB Senin ◽  
HAA Sidek ◽  
GA Saunders
Keyword(s):  
Hydrostatic Pressure ◽  
High Pressures ◽  
Uniaxial Stress ◽  
Elastic Stiffness ◽  
Acoustic Mode ◽  
Elastic Behaviour ◽  
Third Order ◽  
Long Wavelength ◽  
Two Level Systems ◽  
Derivatives Of

The elastic and nonlinear acoustic vibrational properties of terbium metaphosphate glasses (Tb2O3)x(P2O5)1?x with x = 0�226,0�247,0�263 and 0�271 (x is the mole fraction) have been determined from measurements of the effects of temperature, hydrostatic pressure, and uniaxial stress on' ultrasonic wave velocity. At temperatures below about 140 K, the elastic stiffness of' (Tb2O3)x(P2O5)1?x glasses becomes anomalously dependent upon temperature, a behaviour usually associated with interactions between acoustic phonons and two-level systems. Except for the (Tb2O3)0�271(P205)0�729 glass, the hydrostatic pressure derivatives of the elastic stiffness and also of the bulk modulus BS of terbium metaphosphate glasses are small and negative. The third-order elastic stiffness tensor components CIJK of the (Tb2O3)0�247(P2O5)0�753 glass between 77 K and 400 K have also been determined. At room temperature, C112, C123 and C144 are positive while C111, C155 and C456 are negative. Both longitudinal and shear acoustic mode Gr�neisen parameters are small and negative: the application of pressure softens the long-wavelength acoustic phonon mode frequencies. The mode softening is enhanced as the temperature is reduced.

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