Paramagnetic Meissner eect at high ®elds in melt-textured YBa 2 Cu 3 O 7± d F.T. Dias a , P. Pureur a, * , P. Rodrigues Jr. b , X. Obradors c a Instituto de F  õsica, Universidade Federal do Rio Grande do Sul, P.O. Box 15051, 91501-970 Porto Alegre, RS, Brazil b Departamento de F  õsica, UEPG, 84031-510 Ponta Grossa, PR, Brazil c Institut de Ciencia de Materials, CSIC, Campus de la UAB, 08193 Bellaterra, Catalunya, Spain Abstract We observe the paramagnetic Meissner eect in melt-textured YBa 2 Cu 3 O 7± d samples after cooling in ®elds from 1 up to 50 kOe. The results suggest that the paramagnetic moments are primarily generated by compression of the magnetic ¯ux into the sample in the course of the ®eld cooling procedure. We also observe that the ®eld-cooled moments relax towards positive values in experiments performed at constant ®eld and temperature. Ó 2001 Published by Elsevier Science B.V. Keywords: Paramagnetic Meissner eect; Melt-textured YBCO; Field-cooled magnetization Certain granular samples of the high tempera- ture superconductors when cooled in a suciently low magnetic ®eld acquire a paramagnetic moment [1,2]. This unusual eect is known as the para- magnetic Meissner eect PME) and seems to be superimposed to the conventional diamagnetic response. This PME has been attributed to spon- taneous orbital currents which should occur in granular arrays where loops of superconducting grains containing an odd number of p-Josephson junctions are present [3]. This interpretation be- comes credible since p-junctions may occur as a consequence of an order parameter having d-wave symmetry [4]. Several experimental results are in agreement with this interpretation [1,2,5,6]. How- ever, paramagnetic moments have also been ob- served in the superconducting phase of large YBa 2 Cu 3 O 7± d YBCO) crystals [7], small Nb disks [8,9] and in Nb thin ®lms [10]. This fact shows that the PME is not necessarily dependent upon the occurrence of unconventional Josephson junctions in multiconnected superconducting networks. Subsequently, models based on ¯ux compression into the sample have been proposed [11,12]. Ac- cording to authors in Ref. [11], a Bean state with compressed ¯ux and net paramagnetic moment may be stabilized when the sample is inhomoge- neously cooled. If the sampleÕs surface becomes superconducting before some inside region, ¯ux may be forced and compressed into the sample by Lorentz forces generated by the screening currents. An alternative approach [12] proposes the forma- tion of a giant vortex state at the surface critical ®eld, H c3 , as the superconductor is ®eld cooled. With decreasing the temperature, the order pa- rameter develops and compresses the trapped ¯ux Physica C 354 2001) 219±222 www.elsevier.nl/locate/physc * Corresponding author. Fax: +55-51-319-1762. E-mail address: ppureur@if.ufrgs.br P. Pureur). 0921-4534/01/$ - see front matter Ó 2001 Published by Elsevier Science B.V. PII:S0921-453401)00067-3