Quasiparticle density of states

The effective optimized Hamiltonian H, was used to compute quasiparticles density of states, in the vicinity of Fermi energy. The result, shown on Fig. 5, is restricted to an energy window of 2eV on both sides of Fermi... 

Figure 5. Quasiparticles density of states obtained from Gutzwiller method for Plutonium in S phase.

FIGURE 52 Vortex lattice in YNi2B2C imaged by plotting the local quasiparticle density of states at 0.46 K in magnetic fields H applied along the c-axis. (a) m)H = 0 07 T (b) 0.3 T (after Nishimori et al., 2004). 

Our result for RbaCeo differs from a recent determination by scanning tunneling microscopy [26] (A—77 K), possibly because NMR relaxation probes the minimum quasiparticle excitation energy, while tunneling probes the maximum in the quasiparticle density of states, or because of differences between surface and bulk properties. Our NMR relaxation data for Rb3C5o clearly deviate from an Arrhenius law below 8 K. At these tem-... 

The quasiparticle density of states of the Fermi liquid has the form... 

Fig. 47. Schematic quasiparticle density of states N (s) as obtained from the mean-field dispersion, eq. (112). They lead to a hybridization gap centered around , = and two peaks in N e) whose width and separation is also of order The Fermi level (0) is pinned in this region. The temperature dependence of the effective hybridization K, given by the function fl T) = rJ(T)/rJ(0, N = 2) as shown in the inset (Coleman 1987). IF is a slightly renormalized band width [a square DOS of width W has been used for the bare A/,(e)].

Recently, direct measurements of the quasiparticle density of states (DOS) by scanning tunneling spectroscopy on Bi2Sr2CaCu20g+,5 (BSCCO-2212) single crystals as a function... 

A d-f hybridization model according to Brandow (1986) always yields a hybridization gap in the f quasiparticle density of states. The Fermi level can be in the gap or pseudo gap when the Luttinger theorem permits, as e.g. in SmBs, high-pressure SmS or YbBi2, or it can be in a quasiparticle band as in metallic intermediate-valent systems as YbCuAl, CePda or in heavy fermions like UPta, CeAla, CeCug, etc. Quite recently the same theoretical approach has been taken by Czycholl and Schweitzer (1992) and transport and magnetic properties of heavy fermions with a hybridization gap have been calculated in agreement with experiment. 

Another extension of this type of perturbation theory is to the case where there is some additional electronic order in the tip or the sample - for example, magnetic or superconducting order. In the case of magnetic order one is led to consider separate currents of spin-up and spin-down electrons, proportional to the spin-resolved components of the density of states. For a superconductor, the tunnel current depends on the quasiparticle density of states. 

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