Fermi liquid-phase

In the Fermi-liquid phase, the self-energy can be expanded as (Yoshimori and Kasai 1986, Yamada et al. 1987, Yoshimori 1976, Shiba 1975, Nozieres 1974)... 

The important feature of the weak-coupling picture as described above is that F, which is related to the characteristic energy of the Fermi liquid phase still plays the role of the scaling energy. This fact is not surprising since only parts of the Fermi surface contribute to the anomalous properties. One should note however that this theory is not fully self-consistent because the AF fluctuation wave vector is not connected with any FS feature since the latter is assumed as spherical. 

Nearness (even more so) to a conventional Fermi liquid phase upon overdoping, also with rather high 7. ... 

In the metallic state of a conjugated polymer, the charged dopant ions adjacent to the chain induce Frie-del-type oscillations that can enhance the local infrared-active vibrational (IRAV) modes [87]. Thus, strong IRAV modes cannot be interpreted as evidence of a Peierls gap. Salkola and Kivelson [88] proposed that the arrangement of counterions has a strong influence on the nature of the ground state. They proposed that a semimetallic phase intervenes between the nonmetallic (Peierls) and the metallic (Fermi liquid) phases. Park and coworkers [89-92] proposed a soliton-antisoliton condensation model for doped polyacetylene. 

The particles we will deal with in this textbook are mainly electrons and ions in condensed solid and liquid phases. In condensed phases ions are the classical Boltzmann particles and electrons are the degenerated Fermi particles. 

If the SC state is suppressed, the occurrence of a metal-insulator transition (MIT) is expected here at T = 0, at the MIT point in the phase diagram (see Fig. 6), where the metallic phase is of the Fermi-liquid regime, and the insulating phase is of the PG regime of localized electrons and electron pairs within the Hubbard gap. And indeed, experiments where the SC state is suppressed by... 

A third type of semiconductor junction uses a conducting liquid to contact the semiconductor. Generally, the solvent and electrolyte do not participate in the charge-transfer process. Therefore, to control the Fermi level of the liquid phase, a donor/acceptor pair (a redox couple ) must be added to the solution. The electrochemical potential, or Fermi level, of the solution phase is then given by the Nemst equation (equation 8) ... 

As for semiconductor/metal contacts, a change in the Fermi level of the liquid phase should result in a different amount of charge transferred across the semicondnctor/liqnid junction. For semiconductor/liquid junctions, the important energetic trends for a series of different liqnid contacts can thns be determined by measuring the solntion redox potential relative to a standard reference electrode system. Within this model, solutions with more positive redox potentials shonld indnce greater charge transfer in contact with n-type semicondnctors. 

Unfortunately, a problem arises when attempting to compare the electrochemical potential of the solntion and the electrochemical potential of the semiconductor. Like most electronic energy levels for molecules, the Fermi level of the semiconductor is usually determined relative to the vacuum level. Experimental measurements to determine fp.sc for semiconductors (generally through determination of the semiconductor work function and dopant density) yield values that can be related to the energy of an electron in vacuum. However, electrochemical potentials of liquid phases can only be measured as potential differences between the test solution and a solution that is nsed as a reference. Since it is not possible to measure directly the energy of an individual redox couple relative to the vacuum level, it is not possible to determine directly the desired relationship between the energy level on the solid side of the junction and that on the liquid side. 

It follows that the evaluation of the extent to which one-dimensional physics is relevant has always played an important part in the debate surrounding the theoretical description of the normal state of these materials. One point of view expressed is that the amplitude of in the b direction is large enough for a FL component to develop in the ab plane, thereby governing most properties of the normal phase attainable below say room temperature. In this scenario, the anisotropic Fermi liquid then constitutes the basic electronic state from which various instabilities of the metallic state, like spin-density-wave, superconductivity, etc., arise [29]. Following the example of the BCS theory of superconductivity in conventional superconductors, it is the critical domain of the transition that ultimately limits the validity of the Fermi liquid picture in the low temperature domain. 

Figure 5 The generic phase diagram of the (TMfjX as a function of pressure or anion substitution. On the left, the normal phase of sulfur compounds can be described as a Luttinger liquid that becomes gapped in the charge sector (LL, ) below Tj, and can develop either a spin-Peierls (SP) or localized antiferromagnetic ordered state. Under pressure, the properties of the sulfur series evolve toward those of the selenides for which the normal state shows a progressive restoration of a Fermi liquid (FL) precursor to antiferromagnetism (AF) and superconductivity (S), after [28].

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