Carbon 41, 785 (2003)
K. -H. Han, D. Spemann, R. Höhne, A. Setzer, T. Makarova, P. Esquinazi and T. Butz
Article Outline
To calculate the magnetic moments at the sample surface from the data obtained with magnetic force microscopy (MFM), we assumed … that the dipole moment of the tip is located at the tip apex, i.e. at a distance away from the sample surface that equals the scan height h. Within the dipole moment approximation the phase shift ΔΦ due to the interaction between the magnetic moment of the tip and sample depends on h-5 (…). In this case the calculated maximum value of magnetic moment m ~ 2.9 × 10-20 A m2 for the C60 polymer in the region where magnetic domains are visible (pure area A) […]. However, the position of the effective dipole moment of the tip is not necessarily located at the tip apex but at a higher position […], which we call δ, and the change of phase shift with height would depend on (h + δ)-5. If we use δ = 5.2 × 10-7 m (…) we obtain m = 3.6 × 10-15 A m2 for region A, which is 5 orders of magnitude larger than the calculation presented … However, according to our measurements and assuming that a dependence (h + δ)-5 for ΔΦ holds, δ depends on the sample and the sample magnetic conditions (…), indicating that a reliable calculation of the sample magnetic moment from MFM images is difficult.
