Metals, superconduction

The electronic theory of metallic superconduction was established by Bardeen, Cooper and Schrieffer in 1957, but the basis of superconduction in the oxides remains a battleground for rival interpretations. The technology of the oxide ( high-temperature ) superconductors is currently receiving a great deal of attention the central problem is to make windable wires or tapes from an intensely brittle material. It is in no way a negative judgment on the importance and interest of these materials that they do not receive a detailed discussion here it is simply that they do not lend themselves to a superficial account, and there is no space here for a discussion in the detail that they intrinsically deserve. 

M. M. Labes, P. Love and L. F. Nichols, Poly(sulfur nitride) A Metallic, Superconducting Polymer, Chem. Rev., 79, 1 (1979). 

As mentioned before, we shall use small molecules to introduce the fundamentals for more complex molecules, the real core of this book, which will be listed in the next section. Such molecules form solids with remarkable properties (metallicity, superconductivity, ferromagnetism, etc.), some of them at ambient conditions or at much lower hydrostatic pressures than those found for H2 and N2, and some technological applications have been already developed, deserving the name of functional materials. Most of the molecules studied in this book are planar, or nearly planar, which means that the synthesized materials reveal a strong 2D structural character, although the physical properties can be strongly ID, and because of this 2D distribution we shall study surfaces and interfaces in detail. In particular, interfaces play a crucial role in the intrinsic properties of crystalline molecular organic materials and Chapter 4 is devoted to them. 

Labes MM, Love P, Nichols LF (1979) Polysulfur nitride - a metallic, superconducting polymer. Chem Rev 79 1-15... 

The idea is that the particular heterogeneous architectures formed by a superlattice of metallic superconducting units intercalated by a different material can bestow decoherence evading qualities to the system. The... 

Fig. 11 Schematic electronic phase diagram of C q compounds, showing the approximate location of the metal (superconducting)-insulator phase boundary. Open symbols are values of Tc for superconducting fullerides solid symbols indicate TN (ambient pressure) and Tc (>1 GPa) of (NH3)K3C60...

This reproduces the shaip break of the metallic superconduction shown in Fig. 7.1. The absence of the sharp break in the cuprate resistance vs. temperature plot has been attributed to their short coherence lengths which give rise to large thermal fluctuations at the critical temperature. 

Undoubtedly the most exciting reaction of S2N2 is its slow spontaneous polymerization in the solid state at room temperature to give crystalline (SN),. Crystals up to several millimetres in length can be grown. Not only is this an unusually facile topochemical reaction for a solid at low temperature but it results in an unprecedented metallic superconducting polymer, as discussed in the following subsection. 

Felix Bloch (1905-1983), American physicist of Swiss ori n, from 1936-1971 professor at Stanford University. Bloch contributed to the electronic structure of metals, superconductivity, fenomagnetism, quantum electrodynamics and the physics of neutrons. In 1946, independently of E.M. Purcell, he discovered the nuclear magnetic resonance effect. Both scientists received the Nobel Prize in 1952 for the development ot new methods tor nuclesir magnetic precision measurements and the cSscov-eries in connection therewittf. 

The BMS data have been independently analyzed by a different group (Muroi and Street 1995). In this interpretation, it is postulated that the CUO2 planes are either hole-free (insulating) or hole-rich (metallic, superconducting). The three local... 

Comparison of the electronic specific heat of the Ln pnictides with those of the metallic (superconducting) La chalcogenides and those of the degenerate narrow-band (superconducting Tc 0.4 K) semiconductors GeTe (rhomboh.) and SnTe (NaCl type) as well as with that of degenerate p-type germanium, Ag and NiS. (tie = number of conduction elections per formula unit.)... 

The theoretical picture for the N-SmA transition has been succinctly summarized by Lubensky. [28] He explains that there are several important differences between the normal-metal-superconducting and the N-S mA transitions where AT, the splay elastic constant, emerges as a dangerous irrelevant parameter [28]. 

Elementary excitations in the vicinity of a normal metal superconducting metal contact (with D. Saint-James), Phvs. Lett.. 4, 151 (1963). 

The other electron acceptor-C6o compound to be noted is (AsF5)i.88C60 with a bet (a =12.794 A, c= 12.426 A) structure, which can be made by the reaction of Cgo with AsFs in SO2 [81]. However, no intriguing metallic/superconducting or even more magnetic properties are observed in these fullerides. 

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