ISSN:
1573-7357
Keywords:
73.20.Dx
;
74.70.Vy
;
75.40.Gb
;
76.60.Cq
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract We analyze the spectrum of magnetic excitations as observed by neutron diffraction and NMR experiments in Y Ba2Cu3O6+x, in the frame of the single-band t-t′-J model in which the next-nearest-neighbour hopping term has been introduced in order to fit the shape of the Fermi surface revealed in photoemission. Within the slave-boson approach, we have as well examined the d-wave superconducting state, and the singlet-RVB phase appropriate to describe the normal state of heavily-doped systems. Our calculations show a smooth evolution of the spectrum from one phase to the other, with the existence of a spin-gap in the frequency-dependence of χ″(→Q,w)-The value of the threshold of excitations EG is found to increase with doping, while the characteristic temperature-scale Tm at which the spin-gap opens, exhibits a regular decrease, reaching Tc only in overdoped regime. This very atypical combined variation of EG and Tm with doping results of strong-correlation effects in presence o realistic band structure. We point out the presence of a resonance in the w-dependence of χ″(→Q,w) in good agreement with the neutron diffraction results obtained at x = 0.92 and x = 1.0. This resonance is analyzed as a dynamical Kohn anomaly of the second kind in the Cooper channel. Finally, we examine the →q-dependence of the dynamical susceptibility allowing to study the magnetic correlation length ξ as a function of doping, frequency and temperature.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00752305
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