Transport studies of YBa2Cu3Oy/YxPr1-xBa2Cu3Oy and YBa2Cu3Oy/R0.7M0-3MnO3 superlattices, in which R = La or Nd, and M = Ca or Sr

Yang, HC Chen, JC Wang, LM Sung, HH Horng, HE Yang, SY Jeng, JT

Hc. Yang et al., Transport studies of YBa2Cu3Oy/YxPr1-xBa2Cu3Oy and YBa2Cu3Oy/R0.7M0-3MnO3 superlattices, in which R = La or Nd, and M = Ca or Sr, J PHYS CH S, 62(9-10), 2001, pp. 1837-1846

60

INGLESE

Article

Apllied Physucs/Condensed Matter/Materiales Science

JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS

0022-3697 → ACNP

62

9-10

2001

1837 - 1846

ISI

0022-3697(200109/10)62:9-10<1837:TSOYAY>2.0.ZU;2-T

We report the transport studies of Y-Ba2Cu3Oy/YxPr1-xBa2Cu3Oy and YBa(2)Cu( 3)Oy/R1-xMxMnO3 superlattices in magnetic fields in which R = La or Nd, and M = Ca or Sr. The X-ray diffraction of samples shows superlattice structur e. The resistive transition in a magnetic field shows thermal activated beh avior. The flux pinning is reduced when the coupling strength between YBCO layers is decreased. The angular dependence of the critical current of YBa2 Cu3Oy/PrBa2Cu3Oy superlattices reveals the dimensionality of superlattices. The magnetoresistance ratio (MR), \ Delta rho (H = 7T) - Delta rho (H = 0) \/Delta rho (H = 7T), of YBa2Cu3Oy/R1-xMxMnO3 superlattices is affected by the layer coupling of R1-xMxMnO3 layers. The enhancement of the MR ratio in the trilayer YBa2Cu3Oy/La0.7M0.3MnO3/YBa2Cu3Oy film in the low temperature regime is significant and has a value of 33650% at T = 75 K. We attribute this enhancement of the MR to the ordering of magnetic moment in ferromagne tic layers in magnetic fields. The results are discussed in terms of existi ng theories. (C) 2001 Elsevier Science Ltd. All rights reserved.