Observation of asymmetric transverse voltage in granular high-T c superconductors M.S. da Luz a , F.J.H. de Carvalho Jr. a , C.A.M. dos Santos a, * , C.Y. Shigue a , A.J.S. Machado a , R. Ricardo da Silva b a Grupo de Supercondutividade, Departamento de Engenharia de Materiais, FAENQUIL, Polo Urbo Industrial Gleba AI-6, 12.600-970 Lorena-SP, Brazil b Instituto de Fı ´sica ‘‘Gleb Wataghin’’, Unicamp, 13083-970, Campinas-SP, Brazil Received 28 October 2004; received in revised form 15 December 2004; accepted 16 December 2004 Available online 25 January 2005 Abstract This work reports the influence of the granularity on the transverse voltage as a function of the temperature, V XY (T), in polycrystalline samples of Bi 2 Sr 2 Ca 0.8 Pr 0.2 Cu 2 O 8+d composition. It is observed nonzero transverse voltage at zero external magnetic field in the vicinity of the superconducting transition while far away from it, both above and below, no such voltage was detected. Measurements of V XY (T) in both directions of magnetic field allowed to calculate the symmetric and asymmetric transverse voltages in the full range of the applied magnetic field studied (zero up to 9 T). The symmetric transverse voltage as a function of the temperature presents sign reversal of the Hall resistance and positive Hall voltage at normal state such as expected for hole-doped high critical temperature superconductors. On the other hand, the asymmetric component of V XY (T) shows a peak near the superconducting transition which has been recently reported in literature. V XY (T) curves measured in a sample with double superconducting transition, which was confirmed by ac-susceptibility measurements and hysteresis loops of the magneto-resistance, present two peaks in the asymmetric component. These peaks are related to the intergranular and intragranular transitions and can be explained within the framework of Josephson and Abrikosov vortices and anti-vortices motion. By comparing the temperature dependence of the asymmetric transverse voltage and the derivative of longitudinal voltage is possible to observe a specific relation between both transport properties, which is noted to be valid not only at zero applied mag- netic field but also under applied field. Ó 2004 Elsevier B.V. All rights reserved. PACS: 74.25.Fy; 74.50.+r; 74.72.h Keywords: Double superconducting transition; Granularity; Hall effect 0921-4534/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.physc.2004.12.005 * Corresponding author. Tel.: +55 12 3159 9911; fax: +55 12 553 3006. E-mail address: cams@demar.faenquil.br (C.A.M. dos Santos). Physica C 419 (2005) 71–78 www.elsevier.com/locate/physc