Microwave absorption in high- superconductors in low magnetic fields

Abstract

The existence of inter-and intragrain weak links strongly influences the microwave properties of high-temperature superconductors. Considering the properties of a network of resistively shunted, symmetric double contacts, we obtain a consistent description of the high-frequency dissipation in ceramics and single crystals in low magnetic fields. In this model, the temperature dependence of the high-frequency dissipation is determined by the critical current of the weak links and by the penetration depth. The high-frequency absorption line-width decreases when the penetration depth increases with temperature. The results of the measurements of magnetically modulated microwave absorption in single crystals and ceramics are interpreted in terms of the model presented.

The effect of structure on flux instability and on the superconducting properties of the Mo2Re3Bx–Mo3Re2Bxeutectic

“…The discrepancy may, again, be due to the varied sizes and parameters of the intergranular Josephson junctions. When their distribution is flat, as in the theoretical model [34], MMMA exhibits a well-pronounced maximum followed by a plateau for lower temperatures. In our eutectic, the sizes of the superconducting regions vary from fractions of micrometres to several dozen, resulting in a wide distribution of parameters.…”

“…Microwave absorption in granular superconductors can be modelled in terms of the Josephson effect [33][34][35][36][37]. According to such models, in a low temperature range most Josephson junctions are in a superconducting state, with the superconducting grains coupled or, in other words, phaselocked.…”

High-Pressure Microwave Study of YBa2Cu3O7-δ-Pb(Sc0.5Ta0.5)O3Composite

“…When the weak links play a dominant role in the microwave dissipation, one can investigate the low magnetic field-dependent microwave absorption by treating the sample as a network of resistively shunted junctions driven by a microwave small-signal current I1 cos w i t and a dc current I0 induced by an external dc magnetic field. The microwave power absorbed by the junction in linear regime is given by [20][21][22]24]:…”

Superconducting Properties of Mo2Re3Bx-Mo3Re2BxEutectic

“…On further cooling, the MMMA signal starts to increase, attains the maximum and next gradually decreases. This feature can be also modelled in terms of vortices penetration towards the system of the Josephson junctions characterized by various parameters [18][19][20].…”