IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Magnetic Interfaces and Nanostructures Thursday Sessions
       Session MI+TF-ThA

Invited Paper MI+TF-ThA5
Magnetic Reversal of Exchange-coupled Co/Pt Multilayers Probed by Resonant Soft X-ray Scattering

Thursday, November 1, 2001, 3:20 pm, Room 110

Session: Magnetic Thin Films and Surfaces I
Presenter: O. Hellwig, IBM Almaden Research Center
Authors: O. Hellwig, IBM Almaden Research Center
S. Maat, IBM Almaden Research Center
E.E. Fullerton, IBM Almaden Research Center
J.B. Kortright, Lawrence Berkeley National Laboratory
Correspondent: Click to Email
The balance between exchange, anisotropy and dipolar energies determines the domain structure in ferromagnetic films. For systems with perpendicular magnetic anisotropy such as Co/Pt multilayers, this often results in stripe domain patterns. In this study we modify the energy balance in Co/Pt multilayers by selectively replacing Pt layers in the structure by CoO or Ru layers. Adding antiferromagnetic CoO layers leads to a perpendicular exchange bias below the Neel temperature of the CoO. The addition of 0.9-nm Ru layers antiferromagnetically couples adjacent Co/Pt blocks and changes the characteristics of the magnetic reversal behavior dramatically. We use resonant soft X-ray small-angle scattering in addition to more conventional methods such as magnetometry and magnetic force microscopy to investigate the domain structure as well as the magnetic reversal process. By measuring both the angle and field dependence of the magnetic scattering we quantify the domain formation during reversal. For the CoO interlayers we find that the domain nucleation process in the biased samples is asymmetric to positive and negative field sweeps but once nucleated the domain patterns are symmetric to the field sweep directions. Zero field cooling in an aligned stripe domain pattern after in-plane demagnetization results in a periodic biasing of the system. At low temperature this leads to a memory effect in the domain pattern that forms during field reversal. The multilayers with Ru interlayers exhibit two distinct reversal modes that reflect the competition between the dipolar and the interlayer exchange energy. Such systems highlight the opportunity to tune the magnetic domain structure and reversal in perpendicular multilayers. Olav Hellwig was partially supported by the Deutsche Forschungsgemeinschaft via a Forschungsstipendium under the contract number HE 3286/2-1.