Attraction and repulsion forces in melt-textured and sintered YBCO-superconductors: a comparative study/Fuerzas de atraccion y repulsion en superconductors YBCO texturizados y sinterizados: un estudio comparativo

In this paper, we measure the attraction (suspension) and repulsion (levitation) forces produced by the interaction between a permanent magnet and different bulk superconductors. The measurements of the interaction force HTS-PM were carried out with a relatively simple technique developed by us, which is reproducible, reliable and low cost. The obtained results were analyzed with the Bean's critical-state model assuming a uniform magnetic field applied to the superconductor. Two superconducting samples of [YBa.sub.2][Cu.sub.3][O.sub.7-[delta]] (YBCO) prepared by solid-state reaction method and by the melt-textured growth method (MTG) were used. Both samples presented a different hysteresis behaviour in the field cooling (FC) and zero field cooling (ZFC) regimes. Levitation and suspension phenomena were observed in the MTG sample; however, the sintered sample (S) with Oxygen deficiencies ([delta] > 0.15) displayed a slight levitation force but did not show a suspension force, the latter one attributed to a more efficient magnetic flux pinning. Additionally, the critical current density of both samples was determined from the maximum gap of the force ([DELTA]F) in the FC regime. The obtained values were between 43.00 A/[cm.sup.2] and 2,758 A/[cm.sup.2] for the sintered and MTG samples, respectively. These values show a remarkable difference between sintered and MTG samples like that observed from magnetization measurements, which indicate that attraction and repulsion force measurements could provide a rapid and reliable characterization method of polycrystalline superconducting samples. En este articulo medimos las fuerzas de atraccion (suspension) y repulsion (levitacion) producidas por la interaccion entre un iman permanente y diferentes superconductores. Las medidas de la fuerza de interaccion HTS-PM fueron realizadas en un dispositivo sencillo, confiable y de bajo costo. Los resultados obtenidos fueron analizados utilizando el Modelo de Estado-Critico propuesto por Bean bajo la suposicion de un campo magnetico uniforme aplicado al superconductor. Se utilizaron dos muestras superconductoras de [YBa.sub.2][Cu.sub.3][O.sub.7-[delta]] preparadas por el metodo de reaccion de estado solido (S) y por el metodo de texturizado y fundido (MTG). Las muestras presentaron diferente comportamiento de histeresis en los regimenes de field cooling (FC) y zero field cooling (ZFC). Los fenomenos de levitacion y suspension se observaron en la muestra MTG; sin embargo, la m