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 Tuesday Sessions
       Session MI-TuP

Paper MI-TuP10
Investigation of MFM Tip Induced Magnetization Reversal of Magnetic Nanostructures

Tuesday, October 30, 2001, 5:30 pm, Room 134/135

Session: Emerging Materials & Nanostructures Poster Session
Presenter: X. Zhu, McGill University, Canada
Authors: X. Zhu, McGill University, Canada
P. Grutter, McGill University, Canada
V. Metlushko, University of Illinois at Chicago
B. Ilic, Cornell University
Correspondent: Click to Email
Magnetic Force Microscopy (MFM) has become a standard technique to study the magnetic reversal of nanoparticles. However, the magnetic tip stray field contribution to the reversal characteristics has not been systematically investigated. Here we compare data obtained in different operation modes of MFM such as tapping/lift mode or non-contact mode. We investigated e-beam patterned permalloy arrays with nominal thickness of 30nm, with aspect ratios of 1:1 up to 10:1, with widths of 100nm, 150nm and 200nm, and different spacing. Si cantilevers coated with 10nm to 90nm of CoPtCr, NiFe or NiCo are used as magnetic probes. Previously, we have found that the particle moment can easily be reversed when MFM measurements are performed in tapping and lift mode.@footnote 1@ This is associated with the fact that during tapping the tip stray field can be very substantial during part of the tip oscillation cycle. In the present study, we performed MFM measurements in the non-contact mode in our homebuilt vacuum MFM to further characterize how the magnetic tip influences the magnetic sample state. For large tip-sample separation (typically >100nm), and for large aspect ratio particles, we found that the magnetized tip very seldom reverses particle moments. These particles mainly form single domains due to their shape anisotropy. Within a few (<5%), surprisingly, a domain structure was observable. For small tip-sample separation, or small aspect ratio particles, the tip can easily flip the particle moments. From the discontinuity during a single line scan, it is evident that the magnetic moment is suddenly reversed by rotation, even though the MFM does not have temporal resolution. We are in the process of quantitatively characterizing the tip and particle magnetic interaction by correlating the experimental data with micromagnetic simulations. @FootnoteText@ @footnote 1@ X. Zhu, P. Grutter, V. Metlushko, B Ilic, submit to STM'01 conference.