S-wave superconductors

Fig. 24. Magnetic field dependence of the electronic thermal conductivity at T - 0, normalized to its value at Hc2- Circles are for LuNi2B2C, squares for UPt3 and diamonds for Nb. Note the qualitative difference between the activated thermal conductivity of the s-wave superconductor Nb and the roughly linear growth seen in UPt3, a superconductor with a line of nodes (Boaknin et al. 2001).

An unexpected concentration dependence is found for the parameter which describes, according to eq. (8), the deviation of the field dependence of the electronic specific heat in the mixed state from the linear law expected (Nohara et al. 1997) for isotropic s-wave superconductors in the dirty limit. The large deviations from this linear y(H) law observed... 

We found out that interlayer tunneling I-V characteristics at low temperatures essentially differ from those of conventional Josephson junctions between s-wave superconductors. We specify [14] 1) Jc(0) is strongly reduced to compare with the value expected from Ambegaokar-Baratoff (A-B) relation, J(U1 (0) = KO nAa / 2es 2) quadratic and scaling behaviour of [Pg.185]

In contrast to the conventional s-wave superconductor picture above, Gasparov et al. (2006) report unusual temperature dependence of the magnetic penetration depth A.(T) and upper critical field Hc2(T) and propose that ZrBi2 has an unconventional two-gap superconductivity. 

An unexpected concentration dependence is found for the parameter ft which describes, according to Eq. (8), the deviation of the field dependence of the electronic specific heat in the mixed state from the expected linear law (Nohara et al., 1997) for isotropic s-wave superconductors in the dirty limit. The large deviations from this linear y(H) law observed for YNi2B2C become smaller in the quasi-dirty limit, however, they do not completely disappear. It has been pointed out by Lipp et al. (2001) that for intermediate deviations from linearity of y (H), i.e. for = 0.15-0.3, the specific heat data of borocarbides at low magnetic fields can be discussed in the context of the conventional s-wave picture as well as within the... 

YBa2Cu307 is clearly an s-wave superconductor as demonstrated convincingly by the measurements of Harshman et al. [10], Once temperature-activated and field-dependent flux-line disorder are accounted for, the data are fully consistent with s-wave pairing. These data also rule out d-wave pairing. 

The superconducting hole condensate resides in the SrO or BaO planes of most high-temperature superconductors, and in the interstitial oxygen regions of many of the rest, such as Nd Xt- Xu04. All of these superconductors are p-type, s-wave superconductors. 

Now there is an abnndance of non-s-wave superconductors which are frequently associated with anisotropic nodal gap functions where the qnasiparticle excitations of the SC state vanishes on points or hnes on the Fermi surface. This leads to low temperature power law ... 

The residual absorption found in the vast majority of cuprates is not consistent with s-wave symmetry of the superconducting order parameter. Since the DOS inside the gap region of an s-wave superconductor is exactly zero at T = 0, the dissipative part of the conductivity must vanish for a) < 2A, in clear contrast with the experimental data. There have been several attempts to explain the residual absorption in the superconducting state assuming d-wave symmetry. In a d-wave superconductor, the DOS is finite at all finite... 

Note, from eq. (30), that in an s-wave superconductor, the unscreened superconducting-state Raman scattering response, oclm yy, is zero for 0)<2A, but has a scattering... 

Differing from the conventional s-wave superconductors, the symmetry of the Cooper pair in the HTSC has been established by now to be of d-wave symmetry. Its angular dependence was determined by ARPES (angle-resolved photoemission spectroscopy) to be by Loeser et al. (1996) and (Ding et al. 1996). Furthermore, they have... 

It was pointed out that the symmetry of the order parameter, either s-wave or d-wave, should be clarified from tunneling conductance in the vicinity of zero bias. The excitation spectrum of an s-wave superconductor forms discrete bound states, which are equally spaced to A/Ep. On the other hand, several authors (Won and Maid 1996, Maki et al. 1996, Schopohl and Maid 1995, Ichioka et al. 1996) predict, 1 solving the Eilenberger... 

Maggio-Aprile et aL (1995) tentatively interpreted the new peaks at 5.5 mV as the lowest bound state for a vortex in s-wave superconductors. Here, the lowest bound energy is given approximately by = where pf and are the Fermi momentum and... 

Specific heat is also a powerful tool for characterizing superconducting properties of materials. In the case of an s wave superconductor, according to the BCS theory, superconducting specific heat can be described as follows ... 

---