Distribution of vortices in Nb/Al multilayers studied by spin-polarized neutron reflectivity and magnetization

S. W. Han, J. Farmer, P. F. Miceli*, G. Felcher, R. Goyette, G. T. Kiehne, J. B. Ketterson

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

3 Scopus citations

Abstract

We present SPNR and DC magnetization studies of non-uniformly distributed vortices in Nb/Al multilayers for fields applied near-parallel to the film surface. Peaks are observed in the M-H curves that are shown to correspond to vortex row-transitions and the field values of the transitions agree well with free energy calculations. An additional peak is observed at an applied field smaller than the first row-transition field and this is shown to arise from the lower critical field parallel to the surface. Demagnetization effects are discussed. SPNR measurements performed at low field give the London penetration length and measurements in the mixed state are consistent with a single row of vortices residing in the film center, but with positional fluctuations amounting to 1/4 of the film thickness. It is also shown that cycling the applied field leads to a surface-induced reorientation of the vortex magnetic field, which points perpendicular to the surface in zero field.

Original languageEnglish (US)
Pages (from-to)162-172
Number of pages11
JournalPhysica B: Condensed Matter
Volume336
Issue number1-2
DOIs
StatePublished - Aug 2003
EventProceedings of the 7th SXNS - Lake Tahoe, CA, United States
Duration: Sep 23 2002Sep 27 2002

Keywords

  • Nb/Al multilayers, Superconductivity
  • SPNR
  • Spin-polarized neutron reflectivity

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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