Influence of Domain Width on Vortex Nucleation in Superconductor/Ferromagnet Hybrid Structures
- 299 Downloads
We have investigated the effect of spatially inhomogenous magnetic fields on vortex nucleation in magnetically coupled superconductor/ferromagnet hybrid structures. Using low-temperature scanning tunneling microscopy and spectroscopy (LT-STM/STS) we have studied Pb/[Co–Pd] systems with slightly inhomogeneous magnetic domain width throughout the sample. Visualization of the underlying magnetic template structure is achieved through field dependent conductance maps. In the case of zero applied fields, these maps reveal the absence of vortices below a threshold domain width. At those locations with insufficient domain width to support generation of vortices in zero applied fields, nucleation can be restored through the application of an external magnetic field, with vortices nucleating above the domain parallel to the external field. For the magnetic domain width studied in this work, local tunneling spectroscopy reveals uniform superconducting critical temperature as a function of location, despite of local differences in the stray field experienced by the superconductor.
KeywordsSuperconductor-ferromagnet hybrids Vortices and nanostructured superconductors Low-temperature superconductors
Work at Temple University was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-SC0004556. Work at Argonne was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES) under Award No. DE-AC02-06CH11357.