Objective
The last 10 years have seen exceptional developments in solid state physics, particularly in the fields of superconductivity and of small structures: on the one hand, the new high temperature superconductors have been discovered, on the other hand, miniaturization and structuring techniques were developed enabling the fabrication of new artificial devices with novel physical properties (nanophysics). One of the most prominent examples related with superconductivity are the Josephson junction arrays. Both systems exhibit a novel phenomenology characterized by strong fluctuations. These strong fluctuations are due to the specific material parameters in these systems, enhancing the effects of thermal and of quantum fluctuations by many orders of magnitudes as compared to conventional systems. As a consequence, new phase transitions appear such as vortex lattice melting, superconducting layer decoupling, superconductor-insulator transition, super-solid transition, as well as the corresponding new thermodynamic phases. It is the purpose of the present project to investigate the theoretical and experimental aspects of strong fluctuations in these novel superconducting materials and structures.
The project links two groups of scientists from Russia and three groups from the INTAS member states France, The Netherlands, and Switzerland. The theoretical part of the project addresses the strong fluctuations in the vortex system of high Tc superconductors and the phase fluctuations in Josephson junction arrays, in clean systems as well as in the presence of an underlying disorder potential (e.g. representing the effect of the heavy ion irradiation). Both these questions can be mapped to the problem of "interacting dirty bosons". One of the most interesting question in this context is the search for a novel non-superfluid liquid ground state in the boson system with long range interactions. Theoretical studies will be carried out by the two theoretical groups in the network, at the Landau Institute for Theoretical Physics, Moscow (Russia) and at ETH-Zurich (Switzerland). The experimental part of the proposed research addresses two main questions: (i) the properties of the vortex liquid phase in high-TC single crystals and their dependence on heavy-ion irradiation. The samples for this study are grown at Kamerlingh-Onnes Laboratories in Leiden (The Netherlands); the group at the Ecole Polytechnique (France) has access to the irradiation facility at the Grand Acceelerateur National d'lons Lourds (Cean, France). The experimental studies of the properly prepared high Tc samples involve local Hall probeand SQUID-magnetometry as well as transport measurements; (ii) the lowtemperature behaviour near the superconductor-insulator (S-I) transition in high-resistance disordered superconducting alloys and two-dimensional (2D) Josephson arrays in a magnetic field are carried out in the Institute of Solid State Physics, Chernogolovka, Russia. The results of the research will be published in russian and international scientific journals.
Topic(s)
Call for proposal
Data not availableFunding Scheme
Data not availableCoordinator
2300 RA Leiden
Netherlands