D. López, L. Krusin-Elbaum, et al.
Physical Review Letters
We report on measurements of the easy-plane anisotropy field of MgO-based magnetic tunnel junctions. The free layer easy-plane anisotropy field was measured by perpendicular field thermal noise-based ferromagnetic resonance spectroscopy (T-FMR) and by tunneling magnetoresistance (TMR). A model was derived to extract the saturation field of the free layer from perpendicular TMR-based resistance-field data. Both measurements confirm that for 20 Å CoFeB free layers, the measured effective easy-plane anisotropy field of 4π Meff equal to (5.3±0.6) kOe is well below the bulk value based on demagnetization. T-FMR measurements show a base resonant mode with a linear field dependence in accordance with the Kittel formula. Higher-order modes are also observed, suggesting the presence of confined spin-wave excitations. The mode frequency spacing, however, shows significant device-to-device variations whose origin is not yet uniquely determined. © 2010 American Institute of Physics.
D. López, L. Krusin-Elbaum, et al.
Physical Review Letters
J.S. Noh, C.B. Eom, et al.
physica status solidi (b)
X.W. Li, Yu Lu, et al.
Journal of Applied Physics
B. Özyilmaz, A.D. Kent, et al.
Physical Review Letters