List of JRP papers

The 'SpinCal EXL04' Joint Research Project has produced so far:

  • 24 papers in peer-reviewed journals, among which:
  • 5 papers in journals with Impact Factor greater than 5

Publication single view


Vortex Dynamics in Co-Fe-B Magnetic Tunnel Junctions in Presence of Defects

Author(s): M. Kuepferling, S. Zullino, A. Sola, G. Durin, M. Pasquale, G. Bertotti, B. Van de Wiele, K. Rott and G. Reiss
Journal: Journal of Applied Physics
Year: 2015
Volume: 117
Issue: 17
Pages: 17E107
DOI: 10.1063/1.4908142
Abstract: We investigate the frequency of thermally excited vortex oscillations in Co-Fe-B magnetic tunnel junction (MTJ) pillars in the presence of defects. Under a variable in-plane magnetic field, a characteristic behavior is observed: the frequency oscillates from a maximum at certain field values to a steep minimum, which tends towards zero frequency. These frequency variations are described qualitatively well by an analytical model based on the Thiele equation taking into account a single Gaussian pinning potential. It is thus possible to calculate the in-plane depinning field for certain pinning potential parameters. For steep potentials, the depinning is hysteretic and jumps between the pinned and unpinned regime occur due to the presence of an energy barrier. A sharp frequency minimum occurs at an applied field, where a large flat region in the energy landscape is present. From the experiments, the pinning potentials are estimated to be between −0.2eV and −0.4eV. We also perform micromagnetic simulations of the vortex oscillations in the presence of a distribution of pinning centers. The simulations confirm the validity of the Thiele-approach showing that the vortex remains sufficiently rigid.

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