Crossover from S–I–S to S–F–S junctions in composites Y3/4Lu1/4Ba2Cu3O7 + Y3(Al1−xFex)5O12

✍ Scribed by S.I. Popkov; D.A. Balaev; K.A. Shaihutdinov; M.I. Petrov

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 630 KB
• Volume: 460-462
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/j.physc.2007.03.348

✦ Synopsis

The transport properties of the two phases composites based on Y 3/4 Lu 1/4 Ba 2 Cu 3 O 7 (YBCO) and Y 3 (Al 1Àx Fe x ) 5 O 12 (x = 0.0 . . .1.0) have been studied to investigate the effect of magnetic ordering in garnet on superconducting properties of the composites. The composites represent network of Josephson junctions where the non-superconducting ingredient (garnet) acts as barriers separating YBCO grains. It is found that magneto-active ions (Fe) in garnet are responsible for an additional suppression of Josephson coupling in the composites. At some critical concentration of Fe atoms full suppression of super current is observed in a temperature range from T C of YBCO grains down to the characteristic temperature T m . This behavior is attributed to the interaction of super current carriers with spins of Fe atoms located in the barriers. The crossover from S-I-S (S -superconductor, I -insulator) to S-F-S (F -ferrimagnet) junctions is observed in the composites Y 3/4 Lu 1/4 Ba 2 Cu 3 O 7 + Y 3 (Al 1Àx Fe x ) 5 O 12 with x increase.