The,purpose of the thesis is to report the inve?tigation of superconducting phase-periodic conductance oscillations in ferromagnetic wires with interfaces to conventional superconductors. The ferromagnetic wires were made of Holmium(Ho), a conical ferromagnet, and Aluminium(AI) is used as superconductor. The distance between the interfaces was much larger than the singlet superconducting penetration depth. The observed oscillations is explained as due to the long-range penetration of an unusual helical triplet component of the order parameter that is generated at the superconductor/ferromagnet interfaces and maintained by the intrinsic rotating magnetization of Ho. The samples were fabricated using electron-beam lithography and the shadow evaporation technique. This method enables the fabrication of the whole structure without breaking vacuum thus avoiding the formation of Ho oxide barriers at the Ho/ Al interfaces. The films were thermally deposited with first layer of Ho and then Al as second layer. An Al loop is created with a Ho segment to form a Andreev interferometer for the study of superconducting proximity effect.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:504806 |
| Date | January 2008 |
| Creators | Cho, Hsiuchi |
| Publisher | Royal Holloway, University of London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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