Seminars & Lectures
| * TITLE | [JRG Seminar] Interactions of nanoscale ferromagnetic granules in a London superconductor | ||||||
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| * DATE / TIME | 2008-12-16, 15:00 | ||||||
| * PLACE | Hogil Memorial Bldg. 512, APCTP Headquarters, POSTECH, Pohang | ||||||
| * ABSTRACT | |||||||
| Magnetism and superconductivity are two competing collective ordered states in metals. In recent years, however, there has been a great increase in interest in the interactions between ferromagnetism and superconductivity in artificially structured systems. Recent experiments have fabricated structured arrays of ferromagnetic nanoparticles in proximity to a bulk superconductor. We consider the theory of interactions between two nanoscale ferromagnetic particles embedded within a superconductor. In the London limit approximation we show that the interactions between ferromagnetic particles can lead to either parallel or antiparallel spin alignment. The cross over between these is dependent on the ratio of interparticle spacing and the London penetration depth. We show that a phase transition between spin orientations can occur at temperature is varied. Finally we comment on the extension of these results to arrays of nanoparticles in different geometries. We consider the theory spin phase transition also for 2D lattice magnetic dots on the surface of superconductors. We also will give on the short review on the problem of the Kondo effect coupled to superconductivity in ultrasmall grains. |
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