title: Observation of the intense de-pairing effect in YBa(2)Cu(3)O(7-δ) due to the spin injection from La(0.5)Sr(0.5)CoO(3).
abstract: We report experimental evidence for a huge pair breaking effect induced by spin polarized quasiparticles in a YBa(2)Cu(3)O(7-δ)/La(0.5)Sr(0.5)CoO(3) bi-layer fabricated by pulsed laser deposition. The temperature dependent magnetization measurements show evidence for the presence of both ferromagnetic and diamagnetic phases in the bi-layer. The current dependent electrical transport studies in the bi-layer exhibit a significant reduction in the superconducting transition temperature with the increase in applied current as compared to a single YBa(2)Cu(3)O(7-δ) layer and it follows a I(2/3) dependence in accordance with the pair breaking effect. Here, we find that the current driven from a ferromagnetic electrode with low spin polarization, such as La(0.5)Sr(0.5)CoO(3) (-11%), into the superconductor can act as a strong pair breaker. This indicates that the spin polarization of the injecting electrode is not the only criterion in determining the pair breaking effect, rather the transparency of the interface for the spin polarization may also be significant. More interestingly, the spin diffusion length for YBa(2)Cu(3)O(7-δ) has a much longer length scale than that reported earlier in the study of ferromagnetic/superconducting heterostructures.
authors.affiliation: Department of Physics, Indian Institute of Science, Bangalore, 560012, India.
authors.forename: D
authors.initials: D
authors.lastname: Samal
authors.forename: P S
authors.initials: PS
authors.lastname: Anil Kumar