Interchain Alignments and Ground State in Organic Ferromagnets

1998 ◽  
Vol 12 (28) ◽  
pp. 1167-1174
Author(s):  
W. Z. Wang ◽  
K. L. Yao ◽  
H. Q. Lin
Keyword(s):  
Spin Density ◽  
Ground State ◽  
Main Chain ◽  
Phonon Coupling ◽  
Structure Transition ◽  
Interchain Coupling ◽  
Ferromagnetic Structure ◽  
Phase Alignment ◽  
Electron Phonon Coupling ◽  
Organic Ferromagnets

Two kinds of alignments of two neighboring π-conjugated organic ferromagnetic chains are studied by considering the itinerary of electrons, electron–phonon coupling, the Hubbard repulsion and the interchain coupling. It is shown that the out-of-phase alignment is a more stable ferromagnetic structure than in-phase alignment. For out-of-phase alignment, there is a structure transition at a critical interchain coupling, at which the dimerizations of two chains have the same size and reverse sign. Interchain coupling results in transfer of spin density between each main chain and the side radicals.

THE CHARGE-DENSITY WAVE INDUCED BY INTERCHAIN COUPLING IN π-CONJUGATED ORGANIC FERROMAGNETS

2000 ◽  
Vol 14 (21) ◽  
pp. 773-780
Author(s):  
J. P. TIAN ◽  
W. Z. WANG
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Main Chain ◽  
Density Wave ◽  
Interchain Coupling ◽  
Electron Phonon Coupling ◽  
Organic Ferromagnets ◽  
A Charge ◽  
Wave Induced ◽  
Transfer Term

Considering the itineracy of electrons, electron–phonon coupling, the Hubbard repulsion and interchain coupling, we deal with two neighboring-conjugated organic ferromagnetic chains with a numerical method. The interchain coupling is considered as an interchain electron-transfer term, which is different with respect to different sites in chains. The result shows that the interchain coupling can result in a charge-density wave (CDW) along the main chain and a spin-density transfer between the main chain and the side radicals.

LATTICE DYNAMICS AND ANYON SUPERCONDUCTORS

1990 ◽  
Vol 04 (18) ◽  
pp. 1143-1151 ◽  
Author(s):  
D.M. GAITONDE ◽  
SUMATHI RAO
Keyword(s):  
Magnetic Field ◽  
Gauge Field ◽  
Spectral Function ◽  
Carrier Concentration ◽  
Ground State ◽  
Lattice Dynamics ◽  
Phonon Coupling ◽  
Dominant Effect ◽  
Electron Phonon Coupling ◽  
New Type

We consider a model of anyons—fermions coupled to a statistical gauge field—also coupled to phonons via the usual electron-phonon coupling. We study the phonon response when the system is in the superconducting anyon ground state and show the existence of peaks in the phonon spectral function whose frequencies shift with carrier concentration. We suggest that when the electron-phonon coupling is the dominant effect, there could arise a new type of BCS ground state with a spontaneously generated P and T violating supercurrent, that expels the statistical magnetic field.

Bound polaron in a narrow-band polar crystal

1993 ◽  
Vol 71 (11-12) ◽  
pp. 493-500
Author(s):  
Y. Lépine ◽  
O. Schönborn
Keyword(s):  
Effective Mass ◽  
Ground State ◽  
Narrow Band ◽  
Wave Functions ◽  
Phonon Coupling ◽  
Polar Crystal ◽  
Bound Polaron ◽  
Narrow Bandwidth ◽  
Electron Phonon Coupling ◽  
Shallow Impurities

The ground-state energy of a bound polaron in a narrow-band polar crystal (such as a metal oxide) is studied using variational wave functions. We use a Fröhlich-type Hamiltonian on which the effective mass approximation has not been effected and in which a Debye cutoff is made on the phonon wave vectors. The wave functions that are used are general enough to allow the existence of a band state and of a self-trapped state and are reliable in the nonadiabatic limit. We find that three ground states are possible for this system. First, for small electron–phonon coupling, moderate bandwidth, and shallow impurities, the usual effective-mass hydrogenic ground state is found. For a narrow bandwidth and a deep defect, a collapsed state is predicted in which the polaron coincides with the position of the defect. Finally, for moderate electron–phonon coupling, narrow bandwidth, and a very weak defect, a self-trapped polaron in a hydrogenic state is predicted. Our conclusions are presented as asymptotic expansions and as phase diagrams indicating the values of the parameters for which each phase can be found.

Stability and Spin Density in Doped Quasi-One-Dimensional Non-Conjugated Organic Ferromagnets

1998 ◽  
Vol 12 (27) ◽  
pp. 1125-1132 ◽  
Author(s):  
K. L. Yao ◽  
M. Zhao ◽  
Z. L. Liu
Keyword(s):  
Spin Density ◽  
Main Chain ◽  
Density Wave ◽  
Spin Density Wave ◽  
Ferromagnetic State ◽  
One Dimensional ◽  
Amplitude Distortion ◽  
Organic Ferromagnets ◽  
The Stability

The effects of polarons on the stability of ferromagnetic state in doped quasi-one-dimensional non-conjugated organic ferromagnets are investigated. It is shown that spin density wave of doped main chain near the polaron appears amplitude distortion which changes the stability of the ferromagnetic state. If the spins of polarons along the main chain are contrary to those of side radicals' electrons, the stability of the ferromagnetic state will be strengthened. Under the opposite condition, the stability will be weakened.

SELF-TRAPPING TRANSITION OF ACOUSTIC POLARON IN SLAB

2013 ◽  
Vol 27 (08) ◽  
pp. 1350050
Author(s):  
JUNHUA HOU ◽  
XIAOMING DONG ◽  
XIAOFENG DUAN
Keyword(s):  
Ground State Energy ◽  
Ground State ◽  
State Energy ◽  
Alkali Halides ◽  
2D Systems ◽  
Phonon Coupling ◽  
Length Unit ◽  
First Derivative ◽  
Electron Phonon Coupling ◽  
Self Trapping

Self-trapping transition of the acoustic polaron in slab is researched by calculating the polaron ground state energy and the first derivative of the ground state energy with respect to the electron–phonon coupling. It is indicated that the possibility of self-trapping transition for acoustic polaron in slab fall in between 3D and 2D systems. The electron may be self-trapped in slab systems of GaN , AlN and alkali halides, if the slab systems are thinner than one over ten of the length unit ℏ/mc.

PROPERTIES OF IMPURITY BOUND MAGNETOPOLARON IN QUANTUM RODS

2011 ◽  
Vol 25 (01) ◽  
pp. 21-30
Author(s):  
WEI XIAO ◽  
JING-LIN XIAO
Keyword(s):  
Binding Energy ◽  
Aspect Ratio ◽  
Ground State ◽  
Coupling Strength ◽  
Vibrational Frequency ◽  
Cyclotron Frequency ◽  
Phonon Coupling ◽  
Ground State Binding Energy ◽  
Electron Phonon Coupling ◽  
Bound Magnetopolaron

The Hamiltonian of a quantum rod with an ellipsoidal boundary is given after a coordinate transformation, which changes the ellipsoidal boundary into a spherical one. We then study the vibrational frequency and the ground state binding energy of the weak-coupling impurity bound magnetopolaron in it. The effects of the aspect ratio of the ellipsoid, the transverse effective confinement lengths, the electron-phonon coupling strength, the magnetic field cyclotron frequency and the Coulomb bound potential are taken into consideration by using linear combination operator method. It is found that the vibrational frequency and the ground state binding energy will increase with increasing Coulomb bound potential and the cyclotron frequency. They are decreasing functions of the aspect ratio of the ellipsoid and the transverse effective confinement lengths, whereas the ground state binding energy is an increasing function of the electron-phonon coupling strength.

scholarly journals Raman scattering study of spin-density-wave order and electron-phonon coupling in Ba(Fe1−xCox)2As2

2011 ◽  
Vol 84 (10) ◽  
Author(s):  
L. Chauvière ◽  
Y. Gallais ◽  
M. Cazayous ◽  
M. A. Méasson ◽  
A. Sacuto ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Spin Density ◽  
Density Wave ◽  
Spin Density Wave ◽  
Phonon Coupling ◽  
Electron Phonon Coupling ◽  
Scattering Study

A CONCISE APPROACH FOR ONE-DIMENSIONAL HOLSTEIN MODEL

2007 ◽  
Vol 21 (23n24) ◽  
pp. 4230-4233 ◽  
Author(s):  
QING-BAO REN ◽  
QING-HU CHEN
Keyword(s):  
Ground State ◽  
Variational Approach ◽  
Higher Dimensions ◽  
Density Matrix Renormalization Group ◽  
Phonon Coupling ◽  
One Dimensional ◽  
Density Matrix Renormalization ◽  
Holstein Model ◽  
Electron Phonon Coupling ◽  
Good Agreement

A concise variational approach is to propose to calculate the ground-state properties of none-dimensional Holstein model. The results in the weak and strong coupling limit can be easily recovered analytically. It is shown that, in the nontrivial intermediate electron-phonon coupling regime, the present results are in good agreement with those by density-matrix renormalization group and numerical exact diagonalizations. The present approach is more concise than any other analytical ones in this field, and can be easily generalized to Holstein models in higher dimensions and with more electrons.

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