Conductivity, normal state

Keywords Electron doped cuprates, optical conductivity, normal state gap... 

There is assumed to be no interaction between the superfluid and normal components, thus the superfluid component can diffuse very rapidly to a heat source where it absorbs energy by reverting to the normal state. It thereby produces the very high effective thermal conductivity observed in helium II. 

In Section 3.10, we have seen that the thermal conductivity of a superconducting metal can become very small at temperatures well below the transition temperature Tc (about 1/10 of Tc) it can be orders of magnitude smaller than the thermal conductivity of the same material in the normal state. Some metals can be easily switched from the superconducting to the normal state by applying a moderate magnetic field (10 2-10 1 T). 

The neutral insulator TMTSF, which shows field-effect conduction with /Th — 0.2 cm s (Nam et al, 2003), when transformed into a Bechgaard salt also becomes superconducting, but at lower temperatures. In this case the perfect segregation of organic and inorganic molecular planes leads to confined electronic systems, which in the normal state are quasi ID. Organic superconductors based on the BEDT-TTF molecule represent the case of pure 2D electronic systems. 

Children with internalizing disorders such as depression and anxiety are often the best informants about their affective states. However, if children experience depressed or anxious mood as their normal state, no baseline frame of reference is available for comparison. Children and adolescents with externalizing disorders such as ADHD and conduct disorder are often poor informants and may be minimally cooperative with the interview. Since they often deny the existence of a problem and blame others, reports from other informants (parent, school) are essential. 

The two-phase nature of all ceramic samples of the electron-doped superconductors probably accounts for their less desirable properties, including low Meissner fractions in many samples, low and nonmetallic conductivity in the normal state, and... 

Investigations of the normal state magnetoresistance (MR) as well as the Hall effect and the thermal conductivity in the normal and superconducting mixed states give an important information about the electronic structure and the properties of vortex lattice of the investigated materials. 

The superconducting properties induced in the normal metal manifest themselves in many different ways, including energy-dependent transport properties and a modification of the local density of states. For instance, the conductance of a normal conductor connected to a superconducting electrode shows a striking re-entrant behavior [4]. At non-zero temperature and/or bias, the conductance of the normal metal is enhanced as compared to the normal-state. At zero temperature and zero bias, the expected conductance coincides with the normal-state value. The conductance has therefore a non-monotonous behavior. 

Figure IV 2 10. Solid triangles show temperature dependence of the out-of-plane quasiparticle conductivity ac (a) and in-plane quasiparticle conductivity Gab (b). Below Tc they are extracted from the JFF experiment on BSCCO long stack [17] and above Tc they represent the normal state conductivities of whiskers measured independently on samples from the same batch. Open circles correspond to the oc data from Ref. 14, obtained on small mesas in zero field, open squares correspond to 14.4 GHz microwave data for cab from Ref. 18 obtained on epitaxial films. Solid lines in both plots are just guides for the eye. Insert in (a) shows the low temperature part of ac(T) plotted versus T2...

Abstract We will summarize here some of our measurements of the superconducting fluctuations effects on the in-plane electrical resistivity (the so-called in-plane para-conductivity) in La2-i-SrTCu04 thin films with different Sr content. Our results suggest that these superconducting fluctuations effects are not related to the opening of a pseudogap in the normal-state of underdoped compounds. 

---