Transport in some Alkalis

1971 ◽  
Vol 49 (14) ◽  
pp. 1952-1966 ◽  
Author(s):  
B. Hayman ◽  
J. P. Carbotte
Keyword(s):  
Alkali Metals ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Frequency Distributions ◽  
Pseudopotential Theory ◽  
Electrical Resistivities ◽  
The One ◽  
Analysis Of Dispersion ◽  
Uniform Scaling ◽  
Measured Volume

We have calculated the constant pressure and constant volume ideal electrical resistivities of the alkali metals Na, K, and Rb. In addition we have also calculated the ideal thermal resistivities of K and Rb. Information about the phonons is taken from a Born – von Kármán force constant analysis of dispersion curves at a particular temperature, obtained from inelastic neutron scattering. The shifts in phonon frequencies with volume are accounted for, approximately, by a uniform scaling using the known Grunëisen parameter and the measured volume changes. The electron–ion interaction is treated in pseudopotential theory and the one parameter Ashcroft form is used throughout. The calculations are reformulated in terms of two "transport frequency distributions", [Formula: see text] and [Formula: see text], which allow volume and temperature effects to be treated simply. The results compare very favorably with experiment over a wide temperature range.

scholarly journals SPECTRAL PROPERTIES OF MAGNETIC EXCITATIONS IN CUPRATE TWO-LEG LADDER SYSTEMS

2005 ◽  
Vol 19 (24) ◽  
pp. 1179-1205 ◽  
Author(s):  
KAI P. SCHMIDT ◽  
GÖTZ S. UHRIG
Keyword(s):  
Spectral Properties ◽  
Bound States ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Spin Interaction ◽  
Complete Understanding ◽  
Magnetic Excitations ◽  
Recent Developments ◽  
Microscopic Modeling ◽  
The One

This article summarizes and extends the recent developments in the microscopic modeling of the magnetic excitations in cuprate two-leg ladder systems. The microscopic Hamiltonian comprises dominant Heisenberg exchange terms plus an additional four-spin interaction which is about five times smaller. We give an overview over the relevant energies like the one-triplon dispersion, the energies of two-triplon bound states and the positions of multi-triplon continua and over relevant spectral properties like spectral weights and spectral densities in the parameter regime appropriate for cuprate systems. It is concluded that an almost complete understanding of the magnetic excitations in undoped cuprate ladders has been obtained as measured by inelastic neutron scattering, inelastic light (Raman) scattering and infrared absorption.

Crystal Dynamics of Rubidium. I. Measurements and Harmonic Analysis

1973 ◽  
Vol 51 (6) ◽  
pp. 657-675 ◽  
Author(s):  
J. R. D. Copley ◽  
B. N. Brockhouse
Keyword(s):  
Single Crystal ◽  
Harmonic Analysis ◽  
Alkali Metals ◽  
Phonon Frequency ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Lattice Vibrations ◽  
Atomic Force ◽  
Instrumental Resolution ◽  
Crystal Dynamics

Dispersion curves for lattice vibrations propagating along the five major symmetry directions in a single crystal of rubidium have been measured using inelastic neutron scattering. Care has been taken to identify spurious peaks in the neutron groups and to correct for effects of instrumental resolution. The results, at 12, 85, 120, and 205 °K, have been analyzed within the harmonic framework to yield atomic force constants, which were used to compute the phonon frequency distribution and frequency contours in the (100) and [Formula: see text] planes. A reciprocal space analysis has also been performed. The results are compared with previous measurements on the lighter alkali metals, and with the calculations of Toya and of Price, Singwi, and Tosi.

PROXIMITY OF THE METAL-INSULATOR/MAGNETIC TRANSITION AND ITS IMPACT ON THE ONE-ELECTRON SPECTRAL FUNCTION: A DOPING-DEPENDENT ARPES STUDY

2000 ◽  
Vol 14 (29n31) ◽  
pp. 3596-3601 ◽  
Author(s):  
J. MESOT ◽  
A. KAMINSKI ◽  
H. M. FRETWELL ◽  
S. ROSENKRANZ ◽  
J. C. CAMPUZANO ◽  
...  
Keyword(s):  
Spectral Function ◽  
Inelastic Neutron Scattering ◽  
Magnetic Transition ◽  
Inelastic Neutron ◽  
Scattering Data ◽  
Metal Insulator ◽  
Long Range Interactions ◽  
Wave Symmetry ◽  
Intimate Relation ◽  
The One

The doping dependence of the low-temperature spectral function is precisely determined from angle resolved photoemision (ARPES) measurements. It is found that, as the doping decreases, the maximum of the superconducting gap increases, but the slope of the gap near the nodes decreases. Though consistent with d-wave symmetry, the gap with underdoping cannot be fit by the simple cos(kx)-cos(ky) form. We suggest that this arises due to the increasing importance of long range interactions as one approaches the insulator. It is also shown that the shape of the spectral function at the (π, 0) point below T c can be explained by the interaction of the electrons with a collective mode whose energy matches that of the magnetic resonance as obtained by inelastic neutron scattering data, and points to the intimate relation of magnetic correlatins to high Tc superconductivity.

Librational motion in the α phase of solid nitrogen. II. Neutron scattering

1977 ◽  
Vol 55 (6) ◽  
pp. 573-577 ◽  
Author(s):  
D. A. Goodings
Keyword(s):  
Neutron Scattering ◽  
Excellent Agreement ◽  
Structure Factor ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Α Phase ◽  
Solid Nitrogen ◽  
Scattering Measurements ◽  
Librational Motion ◽  
The One

An expression is derived for the one-libron coherent inelastic structure factor for neutron scattering by libron modes in the cubic α phase of solid nitrogen. The results of calculations show that for certain modes at the Γ and R points in the first Brillouin zone and for the scattering vector Q along certain directions in reciprocal space the structure factor vanishes. The results are in excellent agreement with the recent inelastic neutron scattering measurements of Kjems and Dolling.

Crystal Dynamics and Electronic Specific Heats of Palladium and Copper

1971 ◽  
Vol 49 (6) ◽  
pp. 704-723 ◽  
Author(s):  
A. P. Miiller ◽  
B. N. Brockhouse
Keyword(s):  
Specific Heat ◽  
Room Temperature ◽  
Constant Pressure ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Frequency Wave ◽  
Frequency Distributions ◽  
Specific Heats ◽  
Lattice Specific Heat ◽  
Crystal Dynamics

Using inelastic neutron scattering, the frequency – wave vector dispersion relations for the lattice vibrations in a single crystal of palladium have been determined at 120, 296, 673, and 853 °K. Analyses of the results have given force-constant models from which frequency distributions have been computed. First-neighbor interactions are dominant, but weaker interactions also exist, extending beyond sixth-nearest neighbors. The total lattice specific heat (harmonic plus anharmonic) at constant pressure has been calculated, using the frequency distribution at 296 °K and the shifts in the frequencies with changing temperature. Similar calculations were also carried out for copper, using the room temperature distribution reported by Svensson et al.; the temperature dependence of the frequencies was established by carrying out measurements along major symmetry directions of Cu at 296, 473, and 673 °K. The electronic specific heats of Cu and Pd have been calculated at temperatures between 0 and 900 °K. The electronic specific heat of Cu agrees well enough with the linear relation Ce = γT for T < 700 °K. For Pd, Ce is anomalously high at low temperatures, in agreement with experiments at helium temperature, but tends to saturate for temperatures > 200 °K.

scholarly journals Decay and renormalization of a longitudinal mode in a quasi-two-dimensional antiferromagnet

2021 ◽  
Author(s):  
Seung-Hwan Do ◽  
Hao Zhang ◽  
Travis Williams ◽  
Tao Hong ◽  
Vasile Garlea ◽  
...  
Keyword(s):  
Theoretical Study ◽  
Inelastic Neutron Scattering ◽  
Longitudinal Mode ◽  
Wave Theory ◽  
Inelastic Neutron ◽  
Spin Systems ◽  
Longitudinal Modes ◽  
Quantum Magnet ◽  
Energy Mode ◽  
The One

Abstract An ongoing challenge in the study of quantum materials, is to reveal and explain collective quantum effects in spin systems where interactions between different modes types are important. Here we approach this problem through a combined experimental and theoretical study of interacting transverse and longitudinal modes in an easy-plane quantum magnet near a continuous quantum phase transition. Our inelastic neutron scattering measurements of Ba2FeSi2O7 reveal the emergence, decay, and renormalization of a longitudinal mode throughout the Brillouin zone. The decay of the longitudinal mode is particularly pronounced at the zone center. To explain these observations, we develop a generalized linear spin-wave theory, including all of the one-loop corrections, which reproduces the measured mode decay and renormalization. The theoretical approach developed here is broadly applicable to quantum magnets with more than one type of low energy mode.

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