scholarly journals MAGNETIC INCOMMENSURABILITY IN p-TYPE CUPRATE PEROVSKITES

2012 ◽  
Vol 26 (09) ◽  
pp. 1250061 ◽  
Author(s):  
A. SHERMAN
Keyword(s):  
Resonance Peak ◽  
Superconducting Phase ◽  
Itinerant Electron ◽  
Operator Technique ◽  
Zero Temperature ◽  
Electron Theory ◽  
Weak Intensity ◽  
Projection Operator Technique ◽  
Charge Modulation ◽  
P Type

For the superconducting phase with a d-wave order parameter and zero temperature, the magnetic susceptibility of the t–J model is calculated using the Mori projection operator technique. Conditions for the appearance of an incommensurate magnetic response below the resonance frequency are identified. A fast decay of the tails of the hole coherent peaks and a weak intensity of the hole incoherent continuum near the Fermi level are enough to produce an incommensurate response using different hole dispersions established for p-type cuprates, in which such response was observed. In this case, the nesting of the itinerant-electron theory or the charge modulation of the stripe theory is unnecessary for the incommensurability. The theory reproduces the hourglass dispersion of the susceptibility maxima with their location in the momentum space similar to that observed experimentally. The upper branch of the dispersion stems from the excitations of localized spins, while the lower one is due to the incommensurate maxima of their damping. The narrow and intensive resonance peak arises if the frequency of these excitations at the antiferromagnetic momentum lies below the edge of the two-fermion continuum; otherwise the maximum is broad and less intensive.

scholarly journals MAGNETIC RESPONSE OF Pr1-xLaCexCuO4 IN COMPARISON WITH HOLE-DOPED CUPRATES

SPIN ◽  
2014 ◽  
Vol 04 (01) ◽  
pp. 1440006
Author(s):  
A. SHERMAN
Keyword(s):  
Frequency Response ◽  
Projection Operator ◽  
Low Frequency ◽  
Charge Carriers ◽  
Spin Excitation ◽  
Magnetic Response ◽  
Operator Technique ◽  
Projection Operator Technique ◽  
P Type

The origin of differences in the magnetic responses of Pr 1-x LaCe x CuO 4 with x = 0.11–0.12 and moderately doped p-type cuprates is investigated using the t–J model, the Mori projection operator technique and dispersions of charge carriers derived from photoemission experiments. These differences are related to the proximity of the former crystal to the boundary of the antiferromagnetic (AF) phase and to the remoteness of p-type compounds from it. This leads to different nesting vectors of the low-frequency equi-energy contours of carrier dispersions in these crystals. The strong nesting with the AF momentum as the nesting vector produces the commensurate low-frequency response and the coexistence of two spin-excitation branches in Pr 1-x LaCe x CuO 4, while incommensurate nesting vectors in p-type crystals lead to the incommensurate low-frequency response and the hourglass dispersion of susceptibility maxima.

scholarly journals Magnetic Response of Pr1-xLaCexCuO4 in Comparison with Hole-Doped Cuprates

2014 ◽  
Vol 215 ◽  
pp. 11-16
Author(s):  
Alexei Sherman
Keyword(s):  
Magnetic Susceptibility ◽  
Superconducting State ◽  
Projection Operator ◽  
Low Frequency ◽  
Spin Excitation ◽  
Magnetic Response ◽  
Operator Technique ◽  
Electron Band ◽  
Spin Excitations ◽  
Projection Operator Technique

The magnetic susceptibility of the optimally doped Pr1-xLaCexCuO4in the superconducting state is calculated using thet-Jmodel of Cu-O planes, the Mori projection operator technique, and the dispersion of electron bands derived from photoemission experiments. The electron band folding across the antiferromagnetic Brillouin zone border, which is inherent in the crystal, leads to a commensurate low-frequency response. The same band folding causes the appearance of a supplementary spin-excitation branch, which coexists with usual spin excitations. This coexistence can explain two maxima observed in the frequency dependence of the susceptibility. The two nested spin-excitation branches lead to a comb of closely spaced peaks in momentum cuts, which presumably are not resolved in experiment, being seen as a broad commensurate peak up to 100 meV. Reasons for differences in magnetic responses of electron- and hole-doped cuprates are discussed.

HALL-MEISSNER EFFECT IN CHARGED ANYON FLUID AT T → 0

1995 ◽  
Vol 09 (27) ◽  
pp. 3585-3606 ◽  
Author(s):  
E. J. FERRER ◽  
V. DE LA INCERA
Keyword(s):  
Electric Field ◽  
Transverse Electric ◽  
Meissner Effect ◽  
Superconducting Phase ◽  
Effective Theory ◽  
Zero Temperature ◽  
London Penetration Depth ◽  
Magnetic Screening ◽  
Statistical Limit ◽  
Self Consistent

The superconducting behavior of the charged anyon fluid at finite density (µ ≠ 0) and in the zero temperature statistical limit (T → 0) is investigated in a self-consistent way. It is found that total magnetic screening appears only in the presence of a transverse electric field. This electric field is interpreted as a way to simulate, in the linear effective theory, the Hall potential associated with the vortex structure of the charged anyon system. The London penetration depth of the superconducting phase is found to be dependent on the filling factor.

Theory of dissociative recombination and related processes

1974 ◽  
Vol 340 (1622) ◽  
pp. 301-322 ◽  
Keyword(s):  
Energy Spectrum ◽  
Cross Section ◽  
Dissociative Recombination ◽  
Resonance State ◽  
Local Approximation ◽  
Operator Technique ◽  
Final State ◽  
Projection Operator Technique ◽  
Non Local ◽  
Associative Ionization

The theory of dissociative recombination (and the closely related processes of associative ionization and mutual quenching) is developed by using the Feshbach projection operator technique. An expression is given for the cross-section into a specific final state of the dissociating atoms. It is found that the complex potential energy corresponding to a resonance state is non-local in nature and the implications of using a local approximation are considered. The theory of photodissociation through resonances is developed with special reference to the energy spectrum of the products. It is shown that dissociative attachment can be studied without explicitly constructing the intermediate state.

Sign in / Sign up

Export Citation Format

Share Document