Dresden 2006 – scientific programme
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O: Oberflächenphysik
O 33: Scanning probe techniques III
O 33.7: Talk
Thursday, March 30, 2006, 12:45–13:00, PHY C213
Quantitative Dynamic Mode Force Spectroscopy on a Type-II Superconductor Using a Magnetic Tip: Meissner Force, Magnetostatic Tip-Vortex Interaction and Lateral Dragging Force — •Alexander Schwarz1, Ung Hwan Pi1, Marcus Liebmann2, Zheong Gu Khim3, Dong Ho Kim4, and Roland Wiesendanger1 — 1University of Hamburg, IAP, Jungiusstr. 11, 20355 Hamburg — 2Present Address: RWTH Aachen, Department of Physics, 52056 Aachen — 3School of Physics, SNU, Seoul 151-742, South Korea — 4Dept. of Physics, Yeungnam University, Kyungsan, South Korea
In the mixed phase of type II superconductors quantized flux can penetrate the specimen in the form of vortices with a normal conducting core. Using magnetic tips, such samples can be investigated by magnetic force microscopy. We used the frequency modulation technique to study the glass-like flux solid state of a Bi2Sr2CaCu2O8+δ single crystal in the low flux density regime, where neighboring vortices do not overlap. To quantify the distance dependence of the relevant tip-sample interactions, force spectroscopy has been utilized. On top of a vortex, the maximum attraction 18 nm above the surface was determined to be about 5.4 pN. Far away from vortices the Meissner repulsion of about 4.0 pN between the magnetic tip and the superconducting phase dominates the interaction. By taking several force spectroscopy curves across a vortex, the lateral dragging force exerted by a scanning tip on a vortex could be determined to be about 1.5 pN [1]. These results agree well with theoretical predictions.
[1] U. H. Pi et al., Appl. Phys. Lett. 85, 5307 (2004).