Alternative Superconducting Ground States

1960 ◽  
Vol 13 (2) ◽  
pp. 446 ◽  
Author(s):  
JC Fisher
Keyword(s):  
Matrix Element ◽  
Ground State ◽  
Ultrasonic Attenuation ◽  
Spin Projection ◽  
Nuclear Spin Relaxation ◽  
Detailed Knowledge ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Spin Paramagnetism ◽  
Rule Out

A comparison is made between (a) the trial ground state composed of a linear combination of normal state configurations in which individual electron states of opposite momentum and equal spin projection (k t, -k t) and (k t, -k t), abbreviated (kcr, -kcr), are both either occupied or unoccupied, and (b) the trial ground state with (k t , -k t ) pairing proposed by Bardeen, Cooper, and Schrieffer. The two trial states lead to identical thermodynamics as long as an average matrix element -V = < Vkle' >av is treated as a disposable parameter. They lead to similar coherence effects for ultrasonic attenuation and nuclear spin relaxation. They differ in that spin paramagnetism is predicted for (kcr, -kcr) pairing. Detailed knowledge of the electron-phonon interaction in superconductors seems at present inadequate to rule out either possibility for all superconductors.

THE INFLUENCE OF ELECTRIC FIELD ON THE GROUND-STATE LIFETIME OF POLARON IN A PARABOLIC QUANTUM DOT

2011 ◽  
Vol 25 (03) ◽  
pp. 203-210
Author(s):  
WEI-PING LI ◽  
JI-WEN YIN ◽  
YI-FU YU ◽  
JING-LIN XIAO
Keyword(s):  
Quantum Dot ◽  
Electric Field ◽  
Ground State Energy ◽  
Ground State ◽  
State Energy ◽  
Phonon Coupling ◽  
Phonon Interaction ◽  
Strong Electron ◽  
Electron Phonon Interaction ◽  
Parabolic Quantum Dot

The ground-state energy of polaron was obtained with strong electron-LO-phonon coupling by using a variational method of the Pekar type in a parabolic quantum dot (QD). Quantum transition occurs in the quantum system due to the electron-phonon interaction and the influence of temperature. That is the polaron transition from the ground-state to the first-excited state after absorbing a LO-phonon and it causes the changing of the polaron lifetime. Numerical calculations are performed and the results illustrate the relations of the ground-state lifetime of the polaron on the ground-state energy of polaron, the electric field strength, the temperature, the electron-LO-phonon coupling strength and the confinement length of the quantum dot.

ENERGY LEVELS OF A POLARON IN A FINITE PARABOLIC QUANTUM WELL

2001 ◽  
Vol 15 (05) ◽  
pp. 527-535 ◽  
Author(s):  
FENG-QI ZHAO ◽  
XI XIA LIANG ◽  
SHILIANG BAN
Keyword(s):  
Excited State ◽  
Variational Method ◽  
Quantum Well ◽  
Ground State ◽  
Transition Energy ◽  
Energy Levels ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Hole Energy ◽  
First Excited State

The effects of the electron–phonon interaction on the electron (or hole) energy levels in parabolic quantum well (PQW) structures are studied. The ground state, the first excited state and the transition energy of the electron (or hole) in the GaAs/Al 0.3 Ga 0.7 As parabolic quantum well are calculated by using a modified Lee–Low–Pines Variational method. The numerical results are given and discussed. A comparison between the theoretical and experimental results is made.

BINDING ENERGY OF A BOUND POLARON IN THE FINITE PARABOLIC QUANTUM WELL

2001 ◽  
Vol 15 (20) ◽  
pp. 827-835 ◽  
Author(s):  
FENG-QI ZHAO ◽  
XI XIA LIANG
Keyword(s):  
Binding Energy ◽  
Quantum Well ◽  
Ground State Energy ◽  
Ground State ◽  
State Energy ◽  
Transition Energy ◽  
Energy Levels ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Bound Polaron

We have studied the effect of the electron–phonon interaction on the energy levels of the bound polaron and calculated the ground-state energy, the binding energy of the ground state, and the 1 s → 2 p ± transition energy in the GaAs/Al x Ga 1-x As parabolic quantum well (PQW) structure by using a modified Lee–Low–Pines (LLP) variational method. The numerical results are given and discussed. It is found that the contribution of electron–phonon interaction to the ground-state energy and the binding energy is obvious, especially in large well-width PQWs. The electron–phonon interaction should not be neglected.

scholarly journals E⊗e Jahn–Teller Effect in ${\rm C}_{70}^{3-}$ Systems

1997 ◽  
Vol 11 (16) ◽  
pp. 1969-1978 ◽  
Author(s):  
Lin Tian ◽  
Ya-Sha Yi ◽  
Chui-Lin Wang ◽  
Zhao-Bin Su
Keyword(s):  
Ground State ◽  
Berry Phase ◽  
Lattice Relaxation ◽  
Teller Effect ◽  
Phonon Interaction ◽  
Final State ◽  
Electron Phonon Interaction ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Extra Electron

The electron–phonon interaction in C 70 anions is studied by making use of a lattice relaxation approach. We find there exists a Jahn–Teller effect in [Formula: see text] system, due to an extra electron being doped to the double degenerate [Formula: see text] state. As a result of this effect, the original D5h symmetry of the ground state becomes unstable, which causes distortion of the lattice configuration. The only symmetry maintained in the final state of the relaxation is the x–y plane reflection symmetry. We further find that besides the Jahn–Teller active [Formula: see text] modes, the non-Jahn–Teller active [Formula: see text] vibrations also contribute to the relaxation process. The [Formula: see text] components come from the nonlinear effect and are two or three orders smaller than those of the Jahn–Teller active modes. We suggest that the [Formula: see text] molecule is a promising Berry Phase candidate in this effective E⊗e Jahn–Teller system.

Charge Transport and Ultrasonic Properties of La1/3Sr2/3Fe0.95Co0.05O3Perovskite

2012 ◽  
Vol 482-484 ◽  
pp. 819-823
Author(s):  
Hui Kong ◽  
Wei Dai ◽  
Shuai Shao
Keyword(s):  
Single Phase ◽  
Ultrasonic Attenuation ◽  
Charge Ordering ◽  
Simultaneous Occurrence ◽  
Phonon Interaction ◽  
Strong Electron ◽  
Electron Phonon Interaction ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Ordering Transition

The longitudinal ultrasonic velocity (V) and attenuation at a frequency of 10MHz have been measured in single-phase polycrystalline La1/3Sr2/3Fe0.95Co0.05O3 from 20K to 300K. The temperature dependence of resistivity indicates that La1/3Sr2/3Fe0.95Co0.05O3 undergoes charge ordering transition at TCO. A dramatic increase in V is observed at TCO, which is accompanied by a sharp peak in attenuation. This simultaneous occurrence of resistivity and ultrasonic anomalous features implies extremely strong electron-phonon interaction, which is due to the the Jahn-Teller effect of high-spin Fe4+. Below TCO, another softening in V accompanied by a wide ultrasonic attenuation peak is observed. The analysis of the results suggests that these anomalies may correspond to the breathing-type distortion of Fe-O octahedron.

Co-existence of charge order and spin Peierls lattice distortion in one-dimensional organic compounds

2002 ◽  
Vol 12 (9) ◽  
pp. 205-209
Author(s):  
H. Seo ◽  
M. Kuwabara ◽  
M. Ogata
Keyword(s):  
Ground State ◽  
Lattice Distortion ◽  
Charge Order ◽  
Combined Effects ◽  
Strongly Correlated ◽  
Coulomb Interactions ◽  
Phonon Interaction ◽  
One Dimensional ◽  
Electron Phonon Interaction ◽  
Ordered State

The ground state properties of the organic spin-Peierls compounds with one-dimensional quarter-filled band are investigated theoretically. In the strongly correlated regime, two insulating states compete to each other, which are the charge ordered state due to the inter-site Coulomb interaction, and the `dimer Mott' insulating state due to the combined effects of the electron-phonon and the on-site Coulomb interactions. In both of these states, the electron-phonon interaction further produces the lattice tetramization, which is interpreted as the spin-Peierls state.

THE TRANSITION RATE OF THE GROUND STATE OF POLARON IN A PARABOLIC QUANTUM DOT

2009 ◽  
Vol 23 (23) ◽  
pp. 2745-2753 ◽  
Author(s):  
WEI-PING LI ◽  
JI-WEN YIN ◽  
YI-FU YU ◽  
JING-LIN XIAO ◽  
ZI-WU WANG
Keyword(s):  
Quantum Dot ◽  
Ground State Energy ◽  
Ground State ◽  
Transition Rate ◽  
State Energy ◽  
Phonon Coupling ◽  
Phonon Interaction ◽  
Strong Electron ◽  
Electron Phonon Interaction ◽  
Parabolic Quantum Dot

The ground-state energy of polaron was obtained with strong electron-LO-phonon coupling by using a variational method of the Pekar type in a parabolic quantum dot (QD). Quantum transition occurred in the quantum system due to the electron–phonon interaction and the influence of temperature. That is, the polaron transits from the ground state to the first excited state after absorbing a LO-phonon. Numerical calculations are performed and the results illustrate the relations of the transition rate of the polaron on the ground-state energy of polaron, the cyclotron frequency parameter, the Coulomb binding parameter, the temperature, the electron-LO-phonon coupling strength and the confinement length of the quantum dot.

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