Magnetic imaging of layer-by-layer reversal in Co/Pt multilayers with perpendicular anisotropy
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Date
2006-06-15
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American Physical Society
Abstract
For very thin Co layers, the exchange coupling between adjacent Co layers in Co∕Pt multilayers is ferromagnetic and the coupling strength varies nonmonotonically as the nonmagnetic Pt layer thickness (t_Pt) ranges from 3 to 75 Å. We report on the magnetization reversal process in a series of [Co(4 Å)/Pt(t_Pt)]_N multilayers observed by magneto-optical Kerr microscopy as a function of t_Pt and layer repetition N. The images reveal the evolution of magnetic reversal processes that strongly depend on t_Pt and therefore on the interlayer coupling. For Co/Pt multilayers with small t_Pt, e.g., 11 Å, where the Co layers are strongly coupled, the whole multilayer switches as a single ferromagnet. As Co layers are separated farther and become weakly coupled, e.g., at t_Pt=41 Å, layer-by-layer magnetic reversal is observed. The Kerr images reveal metastable magnetic domain configurations during layer-by-layer switching which is not evident in the measured hysteresis loops during the abrupt magnetic reversal for Co∕Pt multilayers with weak interlayer coupling at large t_Pt.
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M. Robinson et al, "Magnetic imaging of layer-by-layer reversal in Co/Pt multilayers with perpendicular anisotropy," Physical Review B 73, no. 22 (2006), doi:10.1103/PhysRevB.73.224422