Superconducting unconventional

In the conventional NMR system used in chemical analyses, downsizing of the spectrometer alone may not be appealing, unless other parts of the system, such as a superconducting magnet, a power amplifier, etc., are also miniaturized. On the other hand, the small-sized spectrometer would find interest in various unconventional scenes. In this section, we show examples of such. 

Tomonaga-Luttinger liquid state [14-16], unconventional superconductivity [17], etc. These molecular conductors once used to be called organic metals, but nowadays this terminology has become obsolete in order to avoid possible confusion with organometallies. ... 

Even at the level of mean field approximation (MFA), the GL theory gives significant information such as penetration depth (l) and coherence length ( ) of the superconducting samples. Many unconventional properties of superconductivity connected with the break down of the simple MFA has been studied both analytically (Tesanovich, 1999)... 

Lefebvre S, Wzietek P, Brown S, Bourbonnais C, Jerome D, Meziere C, Eourmigue M, Batial P (2000) Mott transition, antiferromagnetism, and unconventional superconductivity in layered organic superconductors. Phys Rev Lett 85 5420-5423... 

We defined the parameters of our model and made numerical calculations of temperature dependent of two gaps. It is a qualitative agreement with experiments. We proposed a two channel scenario of superconductivity first a conventional channel (intraband gi) whichis is connected with BCS mechanism in different zone and a unconventional channel (interband gi) which describes the tunneling of a Cooper pair between two bands. The tunneling of Cooper pair also stabilizes the order parameters of superconductivity [9-12] and increases the critical temperature of superconductivity. 

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. 

Thus, considering results on y(H) only, a possible unconventional pairing in borocarbides cannot be ruled out. Similarly it has been noted by Dobrosavljevic-Grujic and Miranovic (2003) that a sizable anisotropy of the s-wave gap function leads to strong deviations for the specific heat in the superconducting state from the predictions of the one-band isotropic BCS-Eliashberg theory. In particular, at low temperatures gap-node like dependencies may appear. 

P. Thalmeier and G. Zwicknagl, Unconventional superconductivity and magnetism in lanthanide and actinide intermetallic compounds 135... 

The onset of electron-phonon interaction in the superconducting state is unusual in term of conventional electron-phonon interaction where one would expect that the phonon contribution is weakly dependent on the temperature [19], and increase at high T. Indeed, based on this naive expectation, this type of unconventional T dependence has been often used to rule out phonons. Here, however, we see clearly that this reasoning is not justified. Moreover, this type of unconventional enhancement of the electron phonon interaction below a characteristic temperature scale is actually expected for other systems such as spin-Peierls systems or charge density wave (CDW) systems. Thus, our results put an important constraint on the nature of the electron phonon interaction in these systems. 

In conclusion, we have shown that according to the doping level in Bi-2212, the onset of superconductivity is associated with a decrease of kinetic energy in the underdoped material, whereas the overdoped material exhibits an increase of kinetic energy. Such a drastic difference confirms that the superconducting state in the underdoped regime of cuprates is unconventional. 

ENHANCED Tc NEAR THE METAL/INSULATOR TRANSITION A NEW PERSPECTIVE ON UNCONVENTIONAL SUPERCONDUCTING MATERIALS... 

While it is clear that the conventional BCS mechanism does not explain the high-temperature superconductivity, the unconventional nature of the e-p coupling suggests that the phonon mechanism cannot be discarded without careful examination. In addition the electronic inhomogeneity observed by the STM/STS measurement4,5 suggests that the inhomogeneity may be an intrinsic nature of the HTSC phenomenon, and any theory on the mechanism has to incorporate this aspect in a fundamental manner. At present no theory can explain both simultaneously. 

Keywords Unconventional superconductivity, disorder, non-.v-wavc scattering, ARPES... 

Chubukov A.V., Pines D., and Schmatian J., (2003). A Spin Fluctuation Model for d-wave Superconductivity in The Physics of Conventional and Unconventional Superconductors eds. by Bennemann K.H. and Ketterson J.B., Vol. 1 (Springer-Verlag). 

Key words superconductivity quantum chemical heterocyclic molecules unconventional superconductors dimer... 

This volume contains the proceedings of the 2004 University of Miami Workshop on Unconventional Superconductivity. The workshop was the fourth in a series of successful meetings on High-Tc Superconductivity and related topics, which took place at the James L. Knight Physics Building on the University of Miami campus in Coral Gables, Florida, in January 1991, 1995, 1999, and 2004. 

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