(1) INESC-MN, R. Alves Redol 9, 1000 Lisboa, Portugal;(2) IFIMUP, Universidade do Porto, R. Campo Alegre, 4100 Porto, Portugal;(3) Department of Physics and Astronomy, University of Glasgow, University Avenue, Glasgow, UK
Abstract:
Exchange bias and blocking temperature were studied in MnPt based
bottom-pinned bilayers and synthetic antiferromagnets (SAF) prepared by
magnetron sputtering. The structure and magnetic properties were determined
as a function of the MnPt layer thickness. Exchange coupling was found to be
(Jex = 0.4 erg/cm2) for a MnPt (t ≤20 nm)/CoFe (5 nm)
bilayer. The distribution of the blocking temperature TB was analyzed
and its width ΔTB and center point TB,center determined.
TB is about 280 ○C for thinner MnPt films, and increases to 330 °C for thick films. ΔT B is constant for thick MnPt but steadily
increases as the thickness decreases. SAF structures show higher exchange
bias and higher TB,center at thin layer thickness (tMnPt = 8.5 nm)
compared to bilayers.