CHARGE-FLUX DENSITY WAVES: ANYONS IN A PERIODIC POTENTIAL

1991 ◽  
Vol 05 (21) ◽  
pp. 1431-1438
Author(s):  
D. M. Gaitonde ◽  
Sumathi Rao
Keyword(s):  
Flux Density ◽  
Periodic Potential ◽  
Mean Field Theory ◽  
Density Wave ◽  
Mean Field ◽  
Landau Levels ◽  
Filling Fraction ◽  
Lattice Periodicity ◽  
Magnetic Length ◽  
A Charge

We show that the lattice periodicity which causes a modulation of the charge density by a wave vector q also leads to a modulation of the flux density if the charged particles are anyons. Within mean field theory, we obtain a charge and flux density wave (CFDW) where the degenerate Landau levels of a constant magnetic field split into bands. For a weak periodic flux superimposed on a strong constant flux, anyon superconductivity at integer filling of Landau levels (corresponding to a statistics parameter of θ = π(1 − 1/ν) with ν = n = integer ) is not affected. However, at statistics corresponding to non-integer filling of Landau levels, for certain commensurability conditions between the lattice length (a), the magnetic length (l) and the filling fraction (ν), gaps open up at the Fermi level and convert an anyon metal into an anyon insulator.

Symmetry Violations in Partially Oxidized One-Dimensional (1D)Transition Metal Polymers. Metal-Ligand-Metal(M-L-M) Bridged Systems

1984 ◽  
Vol 39 (9) ◽  
pp. 807-829
Author(s):  
Michael C. Böhm
Keyword(s):  
Transition Metal ◽  
Density Wave ◽  
Tight Binding ◽  
Mean Field ◽  
Valence Bond ◽  
Hole State ◽  
One Dimensional ◽  
Metal Derivatives ◽  
A Charge ◽  
Metal Ligand

The band structure of the metal-ligand-metal (M-L-M) bridged quasi one-dimensional (1D) cyclopentadienylmanganese polymer, MnCp 1, has been studied in the unoxidized state and in a partly oxidized modification with one electron removed from each second MnCp fragment. The tight-binding approach is based on a semiempirical self-consistent-field (SCF) Hartree-Fock (HF) crystal orbital (CO) model of the INDO-type (intermediate neglect of differential overlap) combined with a statistical averaging procedure which has its origin in the grand canonical ensemble. The latter approximation allows for an efficient investigation of violations of the translation symmetries in the oxidized 1D material. The oxidation process in 1 is both ligand- and metal-centered (Mn 3d-2 states). The mean-field minimum corresponds to a charge density wave (CDW) solution with inequivalent Mn sites within the employed repeat-units. The symmetry adapted solution with electronically identical 3d centers is a maximum in the variational space. The coupling of this electronic instability to geometrical deformations is also analyzed. The ligand amplitudes encountered in the hole-state wave function prevent extremely large charge separations between the 3d centers which are found in ID systems without bridging moieties (e.g. Ni(CN)2-5 chain). The symmetry reduction in oxidized 1 is compared with violations of spatial symmetries in finite transition metal derivatives and simple solids. The stabilization of the valence bond-type (VB) solution is physically rationalized (i.e. left-right correlations between the 3d centers). The computational results derived for 1 are generalized to oxidized transition metal chains with band occupancies that are simple fractions of the number of stacking units and to 1D systems that deviate from this relation. The entropy-influence for temperatures T ≠ 0 is shortly discussed (stabilization of domain or cluster structures).

FRÖHLICH'S ONE-DIMENSIONAL SUPERCONDUCTOR WITH PARA-FERMI STATISTICS

1994 ◽  
Vol 08 (19) ◽  
pp. 1195-1200 ◽  
Author(s):  
V. L. SAFONOV ◽  
A. V. ROZHKOV
Keyword(s):  
Density Wave ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Wave State ◽  
One Dimensional ◽  
Fermi Statistics ◽  
The Mean ◽  
A Charge ◽  
Dimensional Crystal

The hypothesis that conduction electrons in a one-dimensional crystal obey para-Fermi statistics is discussed. Thermal properties of Fröhlich's model in the mean-field approximation are calculated within the framework of this hypothesis. It is shown that the temperature of the phase transition to a charge density wave state is greater in a system with parastatistics.

scholarly journals RECENT ADVANCES IN UNCONVENTIONAL DENSITY WAVES

2004 ◽  
Vol 18 (09) ◽  
pp. 327-344 ◽  
Author(s):  
BALÁZS DÓRA ◽  
KAZUMI MAKI ◽  
ATTILA VIROSZTEK
Keyword(s):  
Cuprate Superconductors ◽  
Mean Field Theory ◽  
Density Wave ◽  
Mean Field ◽  
Temperature Phase ◽  
Pseudogap Phase ◽  
Excitonic Insulator ◽  
Quasiparticle Motion ◽  
Low Temperature Phase ◽  
Electronic Ground

The unconventional density wave (UDW) was speculated on as a possible electronic ground state in the excitonic insulator in 1968. The recent surge of interest in UDW's is partly due to the proposal that the pseudogap phase in high Tc cuprate superconductors is a d-wave density wave (d-DW). Here we review our recent works on UDW's within the framework of mean field theory. In particular, we have shown that many properties of the low temperature phase (LTP) in α-( BEDT-TTF )2 MHg ( SCN )4, with M = K , Rb and Tl , are well characterized in terms of the unconventional charge density wave (UCDW). In this identification the Landau quantization of the quasiparticle motion in a magnetic field (the Nersesyan effect) plays the crucial role. Indeed, the angle-dependent magnetoresistance and the negative giant Nernst effect are two hallmarks of UDW's.

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