AVS 46th International Symposium
    Magnetic Interfaces and Nanostructures Technical Group Thursday Sessions
       Session MI+NS-ThA

Paper MI+NS-ThA3
Progress Toward Achieving Single-Spin Force Detection

Thursday, October 28, 1999, 2:40 pm, Room 618/619

Session: Magnetic Imaging
Presenter: B.C. Stipe, IBM Almaden Research Center
Authors: B.C. Stipe, IBM Almaden Research Center
D. Rugar, IBM Almaden Research Center
H.J. Mamin, IBM Almaden Research Center
C.S. Yannoni, IBM Almaden Research Center
T.D. Stowe, Stanford University
T.W. Kenny, Stanford University
Correspondent: Click to Email
Magnetic resonance force microscopy was originally proposed@footnote 1@ as a method for imaging individual electron or nuclear spins. This talk will focus on recent progress toward achieving the necessary force sensitivity, tip field gradient, and spin lifetime to detect a single electron spin under real experimental conditions (i.e., with a sharp, submicron-size magnet mounted on an ultrasensitive cantilever within 100 Å of a sample surface). Characterization of the magnetic tip is especially important since the field gradient from the tip determines of the force from the spin. In addition, the spin relaxation rate can increase in the presence of magnetic field fluctuations from the tip. We have characterized the magnetic fluctuations of the tip at the cantilever frequency based on field dependent dissipation measurements on both Co thin film and NdFeB particle tips. NdFeB tips showed greatly reduced dissipation/fluctuations due, in part, to their high crystalline anisotropy. These tips should generate field gradients greater than 3 G/Å at the target spin, resulting in a force of more than 30 aN. Using custom fabricated single crystal silicon cantilevers at 2.5 K, we have achieved a force resolution of 2.8 aNHz@super -1/2@ far from the sample surface. However, within 500 Å of the sample, tip-surface interactions can significantly increase the force noise and cantilever frequency jitter. The origin of these effects and methods for reducing them will be discussed. This work is supported, in part, by the Office of Naval Research. @FootnoteText@ @footnote 1@ J.A. Sidles, Phys. Rev. Lett. 68, 1124 (1992).