Magnetic instabilities along the superconducting phase boundary of NbNi multilayers

Amish G. Joshi, Sergiy A. Kryukov, Lance E. De Long, Elvira M. Gonzalez, Elena Navarro, Javier E. Villegas, Jose L. Vicent

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


We report vibrating reed and superconducting quantum interference device magnetometer data that exhibit prominent dips or oscillations of the superconducting (SC) onset temperature, Δ TC (H) ≈0.01-0.7 K, for a [Nb (23 nm) Ni (5 nm)] 5 multilayer (ML) in dc magnetic fields applied nearly parallel to the ML plane. The vibrating reed data exhibit reproducible structures below TC that may reflect multiple SC transitions, but they are sensitive to ac field amplitude and dc field orientation. This striking behavior poses challenges for theoretical and experimental investigations of interfaces between SC and ferromagnetic layers that involve magnetic pair breaking effects, "pi phase shifts" of the SC order parameter, and exotic ("LOFF") pairing states. Alternatively, the anomalies may mark dynamical instabilities within a confined, strongly anisotropic Abrikosov vortex lattice.

Original languageEnglish
Article number09G117
JournalJournal of Applied Physics
Issue number9
StatePublished - 2007

Bibliographical note

Funding Information:
Research at University of Kentucky supported by U.S. Department of Energy and Kentucky Science and Engineering Foundation. Research at Universidad Complutense supported by Spanish Ministerio de Educacion y Ciencia, Comunidad de Madrid y Santander-UCM. One of the authors (A.G.J.) was supported by an Indian Department of Science and Technology BOYSCAST Fellowship No. SR/BY/P-01/04.

ASJC Scopus subject areas

  • General Physics and Astronomy


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