P-wave superconductivity

An interesting theoretical prediction is that, similar as in the p-wave superconductors discussed in the next subsection, non-magnetic impurities in an antiferromagnetic superconductor cause pair breaking (Morozov 1980 Zwicknagl and Fulde 1981) whereas non-magnetic impurities in a non-magnetic superconductor are not expected to destroy superconductivity (Anderson 1959). 

In the presence of Umklapp scattering, the following susceptibilities will be considered for the Peierls channel at 2k% one has the on-site p, = SDW for spin-density-wave and p = BOW for the bond-order-wave in the Cooper channel, one has singlet p = SS and triplet p=TS superconducting correlations. At two-loop level, the auxiliary responses are governed by the flow equations... 

From the anisotropic nature of the superconductivity (d- or p-wave) and the intimate relation between the superconductivity and magnetism, the origin of the attractive force is considered to be due to the antiferro- or ferromagnetic spin fluctuations in HF superconductors. 

The first approach taken was to describe heavy fermions in an analogous way to He, that is by estimating Landau scattering amplitudes and using this to estimate r calculate the pressure dependence of normal and superconducting state properties, etc. Early models, based as they were on He methods, naturally led to p-wave pairing (Vails and Tesanovic 1984, Bedell and Quadar 1985, Fay and Appel 1985, Pethick... 

The e-p interactions, taken as responsible for electron pairing, driving transition into a superconducting state for classical low-Tc superconductors, have almost been abandoned and considered inappropriate to high-Tc cuprates [see e.g. 10]. Some aspects of d - wave superconductivity can be described by strongly correlated electron models e.g. Hubbard - like or t - J models (e.g. [9,13-16]), even without explicit e-p interactions. The underlying leitmotiv in electron correlation treatments... 

The opening of a band gap at in the superconducting state can also be interpreted within this framework. The charge carriers of a superconducting state are not individual electrons as in the normal metallic state but electrons coupled in pairs, the so-called Cooper pairs, having opposite wave vectors. Hence, Cooper pairs are described by product functions (p k)(p —k)). Following the discussion given above. 

Balicas L, Behnia K, Kang W, Canadell E, Auban-Senzier P, Jerome D, Ribault M, Fabre JM (1994) Superconductivity and magnetic field induced spin density waves in the (TMTTF)2X family. J Phys I 4 1539-1549... 

It was shown then that all these observed features can be described self-consistently by Fermi-liquid model for quasiparticles in clean d-wave superconductor with resonant intralayer scattering [14]. The superconducting gap is expressed as A([Pg.185]

E.J. Brandas, L.J. Dunne, J.N. Murrell, Phenomenological Description of d-Wave Condensates of High-Tc Superconducting Cuprates, in J. Maruani et al. (Eds.), New Trends in Quantum Systems in Chemistry and Physics, Kluwer Academic Publishers, Vol. 2, 2000, p. 289. 

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. 

The FS investigations, however, started only after the discovery of the a-phase family (ET)2MHg(FCN)4 with M = K, NH4, Rb, T1 and F = S or Se. The large number of investigations of these compounds is stimulated by the subtle balance between a low-temperature density-wave state and normal metallic and superconducting behavior which can be tuned comparatively easily in the P—B—T parameter space. The coexistence of closed 2D and open ID FS sheets (see Fig. 2.20) gives the possibility investigating the influence of different dimensionalities within the same material. 

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