Unusually strong coherent response from grain-boundary Josephson network in polycrystalline Pr x Y1 − x Ba2Cu3O7 − δ

Abstract

By applying a highly sensitive homemade AC susceptibility technique to P rxY1−xBa2Cu3O 7−δ polycrystals (with x = 0.0, 0.1 and 0.3), we observed very sharp Fraunhofer type low-field periodic oscillations of the real part of the AC susceptibility which were attributed to Josephson vortices penetrating intergranular regions of grain-boundary Josephson network in our samples. Assuming the Lorentz type distribution of single-junction contact areas, we were able to successfully fit the experimental data.

Comparative study on structure and magnetic properties of polycrystalline PrxY1−xBa2Cu3O7−δ prepared in oxygen and argon atmosphere

“…DC measurements were performed using a Quantum Design-MPMS-5 SQUID magnetometer working in the temperature range from 2 to 400 K and the field range from 0 to 200 Oe. AC measurements were performed by using a high-sensitivity homemade susceptometer (operating in the screening method and the reflection configuration [28][29][30]) with the amplitude of 0.1 Oe and the frequency of 35 kHz. …”

On the field-induced diaelastic effect in a small Josephson contact

“…For the explicit temperature dependence of I C (T) we use the analytical approximation of the BCS gap parameter (valid for all temperatures) [17], Δ(T) = Δ(0)tanh with Δ(0) = 1.76k B T C which governs the temperature dependence of the Josephson critical current (11) while the temperature dependence of the London penetration depth is governed by the two fluid model [28]:…”

“…In particular, a remarkable increase of the measurements technique resolution made it possible to experimentally detect such inter esting phenomena as flux avalanches [5], geometric quantization [6], flux driven oscillations of heat capacity [7], reentrant like behavior [8], manifesta tion of π contacts [9], R-C crossover [10], unusually strong coherent response [11], Josephson analog of the fishtail effect [12], geometric resonance and field induced Kosterlitz-Thouless transition [13]. Among the numerous theoretical predictions (still awaiting their experimental verification) one could mention electro and magnetostriction [14], field induced polarization effects [15], analog of magnetoelectric effect [16], nonlinear Seebeck effect and thermal con ductivity [17], stress induced effects [18], chemomag netism [19], magnetoinductance effects [20], implica tions of dipolar interactions for wireless connection between Josephson qubits [21] and for weakening of the Coulomb blockade [22], proximity induced superconductivity in graphene [23] and anomalous Josephson current in topological insulators [24].…”

Analog of the susceptibility spectrum for levitation forces between a superconductor and a permanent magnet

“…2), it has a rather homogeneous grains distribution with an average grain size of the order of 5-10 lm. AC measurements were performed by using a high-sensitivity home-made susceptometer (operating in the screening method and the reflection configuration [33][34][35][36][37][38] ) with the magnetic field amplitude of 0.1 Oe and the frequency of 35 kHz. Fig.…”