Slave-boson method

Keywords High-Tc cuprates, effective band-structure, slave boson method, La2 Sr Cu04... 

In this paper, we show that the observed band-properties can be described within the CT limit of the Emery model, taking into account, beyond the perturbation level, the direct oxygen-oxygen overlap t, treated by the infinite U paramagnetic slave boson method. 

It is also important to note that the slave boson method itself possess two different types of symmetry with respect to doping. From the doping dependence of the effective copper-oxygen overlap t for Ap(i/t0 large enough, symmetry with respect to zero doping emerges [8], since... 

Thalmeier (1988) has calculated the adiabatic bulk modulus of the Anderson Lattice by including a strain dependence of Lkf Lkf —> Kkf + (dVy Vyds)s. Using a slave-boson method for e = 0 and second order perturbation theory with respect to dVkf(V)/ds, he finds... 

Other groups have started with the other extreme, and have generalized the infinite Us approach to the uranium systems. In these approaches, one projects out all the configurations except and/, using a variation on the slave boson methods (Nunes et al. 1985, 1986, Rasul and Harrington 1987, Evans et al. 1989). It is found that these methods are able to account for large enhancements in certain thermodynamic properties, however the spectra still retain marked separations between features in the unoccupied and occupied 5f density of states. 

In section 2, we briefly outline density functional theory and the various approximations employed including the local density approximation (LDA), and discuss generalizations of LDA to incorporate spin (LSDA), orbital, and relativistic effects. We also discuss phenomenological renormalized band schemes based on the slave-boson or Kondo phase-shift methods. 

In the first method, the Landau scattering amplitudes are calculated up to order l/Af in a slave-boson scheme. The 1/N terms represent hybridization (charge) fluctuations. From this, it was found for the Anderson lattice by Lavagna et al. (1987) that a weak instability occurred in the / = 2 (d wave) channel. Soon after, though, Zhang... 

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