Effect of colossal magnetoresistance material La0.67Ca0.33MnO3 on superconducting properties of YBa2Cu3O7-δ thin films

• Published in: Journal of magnetism and magnetic materials 2019-10, Vol.487, p.165335, Article 165335
• Main Authors: Hjelmeland, T.B., Bazioti, C., Gunnæs, A.E., Volkov, Y., Mikheenko, P.
• Format: Article
• Language: English
• Subjects: Colossal magnetoresistance; Colossal magnetoresistance material; Critical temperature; Crystal structure; Curie temperature; Electron spin; Graphene; High temperature superconductor; High temperature superconductors; Magnetic properties; Magnetism; Magnetoresistance; Magnetoresistivity; Nano-magnetism; Quantum computing; Spin injection; Strontium titanates; Substrates; Superconductivity; Temperature; Temperature dependence; Thin films; YBCO superconductors
• ISSN: 0304-8853; 1873-4766
• DOI: 10.1016/j.jmmm.2019.165335

•Multiple contacts allow simple demonstration of the effect of La0.67Ca0.33MnO3 on YBa2Cu3O7-δ.•Spin-polarised current affects both superconducting and normal state of YBa2Cu3O7-δ.•Resistance of bilayer increases below Curie temperature of spin-polarized material.•Spin-polarization creates peak in resistance below the critical temperature.•Graphene solution suppresses superconductivity in polycrystalline YBa2Cu3O7-δ film. By specific design of the sample, in which SrTiO3 substrate is fully covered by a thin layer of the colossal magnetoresistive material La0.67Ca0.33MnO3 (LCMO) and the latter is partially covered by high-temperature superconductor YBa2Cu3O7-δ (YBCO), and by using multiple current and voltage contacts, direct evidence of the strong effect of LCMO on YBCO is obtained. It is found that LCMO strongly influences not only superconducting, but also normal state of YBCO, and it is argued that this is a consequence of the spin injection from the former to the latter. The effect of the deposition conditions and crystal orientation of YBCO layer on this effect is clarified. A surprising peak in the temperature dependence of resistance seen in ex-situ ab-plane oriented sample is explained as a combination of two effects: influence of spin-polarized electrons on superconductor below its critical temperature and the interface-controlled shift of Curie temperature of LCMO to low temperatures. Considering expected use of LCMO and YBCO in composite quantum computation circuits, their combination with another advanced quantum material, graphene, is explored.