The temperature dependence of the resistivity of ferromagnetic metals

1961 ◽  
Vol 263 (1315) ◽  
pp. 473-482 ◽  
Keyword(s):  
Band Structure ◽  
Temperature Dependence ◽  
Fourth Power ◽  
Fractional Change ◽  
Ferromagnetic Metals ◽  
Band Structure Calculations ◽  
Structure Calculations ◽  
Good Agreement

The temperature dependence of the resistivity of nickel and gadolinium has been measured. For nickel, the results are in good agreement with the band-structure calculations of Fletcher (1952); for gadolinium the fractional change in resistivity is almost exactly equal to the fourth power of the reduced magnetization.

scholarly journals Equation of state of condensed matter in laser-induced high-pressure regime

2003 ◽  
Vol 21 (4) ◽  
pp. 523-528 ◽  
Author(s):  
B.K. GODWAL ◽  
R.S. RAO ◽  
A.K. VERMA ◽  
M. SHUKLA ◽  
H.C. PANT ◽  
...  
Keyword(s):  
Band Structure ◽  
Condensed Matter ◽  
Ambient Pressure ◽  
Band Structure Calculations ◽  
Temperature Isotherm ◽  
Shock Hugoniot ◽  
Total Energies ◽  
Pressure Regime ◽  
Structure Calculations ◽  
Good Agreement

We have simulated the shock Hugoniot of copper and uranium based on the results of first principles electronic structure calculations. The room temperature isotherm has been obtained by evaluating the accurate ground state total energies at various compressions, and the thermal and electronic excitation contributions were obtained by adopting isotropic models using the results obtained by the band structure calculations. Our calculations ensure smooth consideration of pressure ionization effects as the relevant core states are treated in the semi-core form at the ambient pressure. The pressure variation of the electronic Grüneisen parameter was estimated for copper using the band structure results, which leads to good agreement of the simulated shock Hugoniot with the measured shock data. The simulation results obtained for U are also compared with the experimental data available in literature and with our own data.

The Fermi surface of beryllium

1964 ◽  
Vol 282 (1391) ◽  
pp. 521-546 ◽  
Keyword(s):  
Band Structure ◽  
Fermi Surface ◽  
Cross Section ◽  
Brillouin Zone ◽  
Field Direction ◽  
Pulsed Magnetic Fields ◽  
Hexagonal Symmetry ◽  
Band Structure Calculations ◽  
Structure Calculations ◽  
Good Agreement

The Fermi surface of beryllium has been determined experimentally by studying the de Haas–van Alphen effect of single crystals in pulsed magnetic fields. The de Haas–van Alphen frequency (proportional to the extremal area of the Fermi surface normal to the field) was measured as a function of field direction. Consideration of the hexagonal symmetry of the Brillouin zone (discussed in the Appendix) shows that only six distinct classes of fre­quency variation with field direction are possible, and these considerations are used to deduce the locations and forms of the various sheets of the Fermi surface. The Fermi surface is found to consist of hole and electron surfaces of equal volume (each containing 0∙162 carrier per atom). The hole surface is somewhat like a coronet, i. e. a ring of six smoothed tetrahedra joined by small necks lying in the central (0001) plane of the first double Brillouin zone, and the electron surface is a set of six roughly ellipsoidal surfaces (cigars) lying on the vertical edges of the second double zone. Detailed shapes and sizes are deduced for the coronet and cigars such that the extremal areas of cross-section are consistent to within 1 % of those obtained from the observed de Haas–van Alphen frequencies. No oscillations of frequency corresponding to the outer (0001) orbit round the coronet were, however, observed; a study of the field dependence of amplitude of the oscillations from the coupled orbit round the cigar shows that this absence can be explained by magnetic breakdown of the {101̄0} band gap. The model described is in good agreement with the predictions of recent band structure calculations, and is consistent with other experimental evidence.

Cems Interface Study of (Fe/M)-Multilayers (M=Cr,Gd)

1991 ◽  
Vol 231 ◽  
Author(s):  
CH. Sauer ◽  
J. Landes ◽  
W. Zinn ◽  
H. Ebert
Keyword(s):  
Band Structure ◽  
Temperature Dependence ◽  
Layer Thickness ◽  
Sandwich Structure ◽  
Magnetic Moments ◽  
Magnetic Interaction ◽  
Interaction Range ◽  
Band Structure Calculations ◽  
Structure Calculations ◽  
Interface Study

AbstractThe temperature dependence of the magnetic hyperfine (hf.) fields near the interfaces in epitaxial Fe/Cr and partly epitaxial Fe/Gd bilayers were measured using 57Fe Conversion Electron Mössbauer Spectroscopy (CEMS). It was found that the Fe-Cr magnetic interaction extends only up to the second Fe-neighbor at the Fe/Cr interface, whereas the interaction range at the Fe/Gd interface is four times larger. For comparison the hf. fields and magnetic moments for Fe/Cr multilayers were obtained performing LMTO (Linear Muffin Tin Orbital) band structure calculations. The Néel temperature of a thin Cr-interlayer in a Fe/Cr/Fe sandwich structure was determined in dependence of the Cr-layer thickness.

Ab-initio Band Structure Calculations and 61 Ni-Mössbauer Studies of BaNiO2 , BaNiO3 and CaNiN

1996 ◽  
Vol 51 (5-6) ◽  
pp. 515-526 ◽  
Author(s):  
B. Hannebauer ◽  
P.C. Schmidt ◽  
R. Kniep ◽  
N. Jansen ◽  
D. Walcher ◽  
...  
Keyword(s):  
Band Structure ◽  
Orbital Method ◽  
Full Potential ◽  
Band Structure Calculations ◽  
Nickel Compounds ◽  
Linear Chains ◽  
Square Planar ◽  
Structure Calculations ◽  
Infinite Linear ◽  
Good Agreement

The electron density distribution of the nickel compounds BaNiO2 , BaNiO3 and CaNiN has been investigated experimentally by 61Ni Mössbauer spectroscopy and theoretically by band structure calculations using the FP-LMTO (Full Potential Linear Muffin-Tin Orbital) method. For all compounds good agreement is found between the experimental and theoretical values of the electric field gradient qexp. and qtheor. at the nickel site.BaNiO2 contains nickel in a square-planar coordination forming puckered chains of edge-sharing NiO4 squares. |q| at nickel is large: qexp = - 15.7(1.5) • 1021 Vm-2 and qtheor. = - 15.59 • 1021 Vm-2 .The principal axis z is perpendicular to the NiO4 squares. The crystal structure of BaNiO3 contains face-sharing chains of NiO6 octahedra. In BaNiO3 q(Ni) is small: qexp. = ± 3.6(2.0) • 1021 Vm-2 and qtheor. = - 1.86 • 1021 Vm-2 . Because of the small broadening of the Mössbauer resonance line the sign of q could not be determined experimentally.The nitridoniccolate CaNiN contains infinite linear chains 1∞[NiN2/2 ] which run perpendicular to the c axis. Unexpectedly, |q(Ni)| in CaNiN is small: qexp. = 0.0 (2.0) • 1021 Vm-2 and qtheor. = - 3.05 • 1021 Vm-2. Again the sign of q(Ni) could not be determined experimentally. It is found theoretically that the small value of q(Ni) is caused by severe cancellation between σ and π contributions.

scholarly journals Design of Graphene Phononic Crystals for Heat Phonon Engineering

Micromachines ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 655 ◽  
Author(s):  
Haque Mayeesha Masrura ◽  
Afsal Kareekunnan ◽  
Fayong Liu ◽  
Sankar Ganesh Ramaraj ◽  
Günter Ellrott ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Band Structure ◽  
Phononic Crystal ◽  
Phononic Crystals ◽  
Neck Length ◽  
Wave Interference ◽  
Band Structure Calculations ◽  
Structure Calculations ◽  
Transmission Spectrum Analysis ◽  
Good Agreement

Controlling the heat transport and thermal conductivity through a material is of prime importance for thermoelectric applications. Phononic crystals, which are a nanostructured array of specially designed pores, can suppress heat transportation owing to the phonon wave interference, resulting in bandgap formation in their band structure. To control heat phonon propagation in thermoelectric devices, phononic crystals with a bandgap in the THz regime are desirable. In this study, we carried out simulation on snowflake shaped phononic crystal and obtained several phononic bandgaps in the THz regime, with the highest being at ≈2 THz. The phononic bandgap position and the width of the bandgap were found to be tunable by varying the neck-length of the snowflake structure. A unique bandgap map computed by varying the neck-length continuously provides enormous amounts of information as to the size and position of the phononic bandgap for various pore dimensions. We have also carried out transmission spectrum analysis and found good agreement with the band structure calculations. The pressure map visualized at various frequencies validates the effectiveness of snowflake shaped nano-pores in suppressing the phonons partially or completely, depending on the transmission probabilities.

scholarly journals Fermi surface of the skutterudite CoSb3 : Quantum oscillations and band-structure calculations

2021 ◽  
Vol 103 (8) ◽  
Author(s):  
M. Naumann ◽  
P. Mokhtari ◽  
Z. Medvecka ◽  
F. Arnold ◽  
M. Pillaca ◽  
...  
Keyword(s):  
Band Structure ◽  
Fermi Surface ◽  
Quantum Oscillations ◽  
Band Structure Calculations ◽  
Structure Calculations

Extrinsic photonic band structure calculations of a doped semiconductor under an external magnetic field

2008 ◽  
Vol 372 (31) ◽  
pp. 5224-5228 ◽  
Author(s):  
Renlong Zhou ◽  
Xuewen Wang ◽  
Bingju Zhou ◽  
Yongyi Gao ◽  
Xiaojuan Liu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Band Structure ◽  
Photonic Band Structure ◽  
Band Structure Calculations ◽  
Photonic Band ◽  
Structure Calculations
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