Effect of ferromagnetism on superconductivity in manganite/cuprate hetero structures

In this investigation, we deposited multilayers of [(La0.67Sr0.33MnO3)(d)/(YBa2Cu3Oy)(x)], [(La0.7Ca0.3MnO3)(4)/(YBa2Cu3O7)(x)](180nm) and [(La0.45Ca0.55MnO3)(4)/(YBa2Cu3O7)(x)](180nm) of varying individual layer thicknesses using the 'eclipse' pulsed laser deposition technique. Transport measurements were performed to obtain the films' critical temperatures (T-c). We study the interaction between superconductivity and magnetism within these heterostructures, paying attention to the superconducting and ferromagnetic coherence lengths, xi(F) and xi(S) respectively, of the materials in the system, and analyzing how these parameters affect the suppression of T-c, eliminating stray field as a possible cause of T-c suppression. We compared our data to previous work to achieve a more comprehensive study of oxide F/S multilayers. We observe that the magnetic nature of the manganite layers do not have much influence on T-c suppression in the multilayers. We show that within certain limits, the thicknesses of both the superconducting and ferromagnetic layers individually affect the T-c of the multilayers. The critical thickness of YBCO in our multilayers was estimated to be similar to20nm. (C) 2004 Published by Elsevier B.V.