AVS 47th International Symposium
    Magnetic Interfaces and Nanostructures Tuesday Sessions
       Session MI+NS+NANO 6-TuM

Paper MI+NS+NANO 6-TuM4
High Anisotropy, High Gradient Magnetic Tips For Magnetic Resonance Force Microscopy

Tuesday, October 3, 2000, 9:20 am, Room 206

Session: Magnetic Imaging I
Presenter: H.J. Mamin, IBM Almaden Research Center
Authors: H.J. Mamin, IBM Almaden Research Center
B.C. Stipe, IBM Almaden Research Center
C.S. Yannoni, IBM Almaden Research Center
D. Rugar, IBM Almaden Research Center
T.D. Stowe, Stanford University
T.W. Kenny, Stanford University
D. Streblechenko, Arizona State University
M.R. Scheinfein, Arizona State University
Correspondent: Click to Email
In magnetic resonance force microscopy (MRFM), imaging is performed by detecting forces on a magnetic tip, but arising from only those spins within a thin resonant slice. To achieve the ultimate goal of single-spin detection, the tip must produce sufficient field gradients, at least 10 G/nm. At the same time, thermal fluctuations in the tip moment must be sufficiently small that the tip does not perturb the spin under study. These requirements have driven us to the use of tips based on high anisotropy, rare-earth bulk magnets. Small particles of NdFeB, PrFeB, and SmCo have been attached to cantilevers and oriented in an external magnetic field. The particles were then sculpted to the desired sub-micron size and shape with a focused ion beam. The magnetic properties have been characterized through cantilever-based magnetometry as well as electron holography. By measuring dissipation and applying the fluctuation-dissipation theorem, we have set upper limits on the low frequency fluctuations in the tip moment. Using a tip optimized for a 1 nm slice thickness, we have detected MRFM signals from on the order of 100 net spins. This work is supported, in part, by the Office of Naval Research.