Superconductors intermediate state

Oxides play many roles in modem electronic technology from insulators which can be used as capacitors, such as the perovskite BaTiOs, to the superconductors, of which the prototype was also a perovskite, Lao.sSro CutT A, where the value of x is a function of the temperature cycle and oxygen pressure which were used in the preparation of the material. Clearly the chemical difference between these two materials is that the capacitor production does not require oxygen partial pressure control as is the case in the superconductor. Intermediate between these extremes of electrical conduction are many semiconducting materials which are used as magnetic ferrites or fuel cell electrodes. The electrical properties of the semiconductors depend on the presence of transition metal ions which can be in two valence states, and the conduction mechanism involves the transfer of electrons or positive holes from one ion to another of the same species. The production problem associated with this behaviour arises from the fact that the relative concentration of each valence state depends on both the temperature and the oxygen partial pressure of the atmosphere. 

Besides the theory of domain structure in antiferromagnets [18] - [21], similar to that of the intermediate state in type 1 superconductors, the suggestion was made [9], [10], that in antiferromagnets a state may be... 

A variety of substances, manifestating intermediate states, which was earlier represented by type 1 superconductors and weakly magnetic metals under conditions of the dHvA effect, is complemented by antiferromagnetic insulators. 

Other possible areas of application of the periodic surfaces, or of disordered relatives of these, include structure of superconductors in the intermediate state (Shal nikov 1941), sintering kinetics (Hench and Ulrich 1984), fluid flow through porous media (e.g., Zick and Homsy 1982), the topology of spacetime at the scale of Planck length (Wheeler 1957), the structure of the prolamellar body in certain plastics (Gunning 1965), certain phase-segregated block copolymers (Thomas et al. 1986 Anderson and Thomas 1988)) semiconductor-... 

Obst has developed a decoration technique for investigating normal and superconducting regions in superconductors. In the intermediate state in lead, the phase boundaries are oriented along cube edges. Other type I superconductors also show correlations between orientation of the flux-line lattice and the crystal lattice. 

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... 

Type 2 This behaviour is not so clear cut. At small values of the applied field, the material behaves in the same way as a type 1 superconductor and there is not penetration by the field. Similarly, at high values of the applied field the field readily penetrates the whole sample. However, at intermediate values, between the two extremes, there is partial penetration by the field and the sample exhibits a complex structure. There are mixed regions in the superconducting and normal state. This is known as the vortex state. This means that in type 2 materials the magnetization diminishes gradually rather than suddenly (Figure 5.28)... 

As we have seen, the Josephson effects appear to occupy an intermediate position between phase transitions and bifurcations to dissipative structure states. One of the reasons for this special behavior of superconductors is that they can carry electric currents without dissipating any energy. There is another reason for the Josephson effects to occupy this intermediate position. In the case of ordinary dissipative structures, the structures are macroscopic and can be described by classical physics. 

Electron-spin resonance (ESR) is an extremely useful tool for probing the localized magnetic moment in a variety of materials. The chapter (162) by Elschner and Loidl focuses on metallic lanthanide systems, reviewing both the classical ESR behaviors and the role of ESR in newly developed branches of solid-state physics. The former includes the determination of the site symmetry of the ESR probe and measurement of the crystal field (CF) and how it (CF) differs in metallic systems from that in insulators. The latter deals with Van Vleck systems, spin glasses, Kondo systems, heavy-fermion and intermediate-valence compounds, and high-temperature superconductors. 

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