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Standing spin waves in ultrathin magnetic films: a method to test for layer-dependent exchange coupling
J Rajeswari1, H Ibach2, C M Schneider1
1Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich, 52425 Jülich, Germany and Jülich Aachen Research Alliance, 52425 Jülich, Germany.
Physical Review Letters
|April 15, 2014
Summary
We developed a new method to test theories of magnetic coupling in thin films using spin waves. This technique successfully validated theories predicting strong interlayer coupling in cobalt films.
Area of Science:
- Condensed matter physics
- Materials science
- Surface science
Background:
- Understanding exchange coupling in ultrathin magnetic films is crucial for spintronic devices.
- Theoretical models predict varying layer dependence of exchange coupling constants, requiring experimental validation.
Purpose of the Study:
- To introduce and validate a novel experimental method for testing theoretical models of layer-dependent exchange coupling.
- To investigate the exchange coupling in ultrathin cobalt films grown on Cu(100).
Main Methods:
- Utilizing high-resolution electron energy loss spectroscopy (HREELS) to observe high-energy, high-momentum standing spin wave modes.
- Comparing experimental data with predictions from different theoretical models.
Main Results:
- Experimental data for 5-8 layer fcc cobalt films on Cu(100) were obtained.
- The results favored theoretical models predicting a large interlayer exchange coupling, which showed better agreement with the observed energy spreading in dispersion curves.
- The surprising success of the nearest-neighbor Heisenberg model was discussed.
Conclusions:
- The developed HREELS method is effective for probing layer-dependent exchange coupling in magnetic films.
- Experimental evidence supports theories with significant interlayer coupling in ultrathin cobalt films.
- Further investigation into the validity of simplified models like the Heisenberg model is warranted.
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