Zero-bias anomaly

Here we have taken the two wires to have the same electron density and strength of the interactions. For not very strong interactions, a 1, the last term in Eq. (6) can be disregarded, away from the regime of the zero-bias anomaly. [7] The integrand in Eq. (6) then has two simple poles yielding... 

Also, tunneling data have been discussed in the framework of unconventional pairing, and theoretical models have also been rewritten. It is claimed that several features such as the zero-bias anomaly observed in transverse geometry are indications of j,2-wave symmetry of the order parameter (see sec. 6), while some of the latest investigations on YBa2Cu30j, show the admixture of s- and d-waves. 

On the other hand, the substitution of Zn (content 1%) showed Tc 79K, and the gap value 2App w 50 meV was almost the same value as that of the pure sample. However, the conductance at zero bias was increased. This increase, estimated to a residual DOS of 0.4, was in good agreement with the results of NMR experiments (Ishida et al. 1993). Their results were compared with theoretical results of impurity effects in d-wave superconductors in the unitary limit (Balatsky and Salkola 1996, Salkola et al. 1996), though they did not claim that the zero-bias anomaly observed in Zn-substituted Bi2212 is explained by their prediction. These variations in the substituent atoms seem to indicate that Co, Zn and Ni affect the electronic states in different ways. 

Another conductivity mechanism could be suggested for LB films of this polymer with Ag+ cations. Such cations can accept or release electrons easily, so in the layer of such cations the conductivity could be caused by electron transitions between the ions with different degrees of oxidation. With tunneling microscopy an anomaly in the dl/dV(V) curves near zero bias was discovered for the LB films in Ag form with an odd number of layers there was a conductivity peak some 150-200 mV wide (Figure 7.4, Curves 1, 3) but no anomaly for these same films with an even number of layers (Figure 7.4, Curve 2). For LB films with an odd number of layers the ordered superstructure of the scale 11.5 x 11.5 x lO cm has been found in a conductivity dl/dV (x,y) measurement regime. The scale of such a structure corresponds to 3 x 2 surface reconstruction (Figure 7.5). 

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