The temperature dependence of the critical current density Jc(T) in superconducting fulleride K3C60 crystals is investigated on the basis of magnetization measurements in these materials. According to ac susceptibility data, the best crystals do not exhibit granularity for supercurrent flows, and can be regarded as single crystals from this point of view. The obtained results on Jc in K3C60 are compared with those for other crystalline and powder-type compounds AxByC60. Possible granularity of the crystals and its influence on Jc are discussed in detail. The irreversibility line for a K3C60 single crystal is also determined.
Magnetic relaxation processes in superconducting fulleride K3C60 are investigated on monocrystalline samples in a wide range of temperatures and magnetic fields. A logarithmic time dependence M(t) of magnetization is observed in samples with 100% of superconducting phase. The normalized relaxation rate increases with temperature in the entire range of magnetic fields. The flux creep activation energy ranges from 10 to 80 meV, and its temperature dependence has a peak. It has been concluded from the results of measurements on samples with nonideal stoichiometry that inhomogeneities strongly affect the relaxation processes and can mask the logarithmic dependence M(t) completely.
Hetero-transitions on a base of InAs and AnSb compounds permitted to obtain cheap light diodes and detectors with the atmosfere maximal transparency region sensibility. There is assumed simultaneously, that the phon radiation in InAs-InAs1Sb is not large, which positively effects on receiver parameters. Changing the composition of InAs-InAs1 Sb solution., one may obtain the structure with the width offorbidden zone ofthe want of 0.35to 0,1 eV.There is developed the heterostructures crystalline lattice parameters determing method (for substrate and film) with the DRON-3M x-ray diffractometer. There was found the nonlinear dependence of the heterostructures lattice parameter on the composition. Investigations of interatomic interaction in dependence on composition and also on the for bidden zone width Eg(x) have show, that solid solutions InAs-lnAs1Sb may be used for the obtaining of infra-red receiver.
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