Fig.1 Basic STM setup. Atomically sharp tip is mounted
on 3 piezo crystals that allow precise positioning in 3 directions.
Moving in (x,y) plane scans the tip across the sample, z piezo
determines the tip-sample distance.
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Fig. 2 Simplified version of Stearns-Julliere model
of spin-polarized tunneling. N's are respective numbers of spin-up,
spin-down electrons in the two materials, a and a* are respective
proportions of spin-up (that is aligned with the field) electrons.
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Fig. 3 Ferromagnetic tip
scanning over alternately magnetized terraces separated by monoatomic
steps. An additional contribution from spin-polarized tunneling
leads to larger apparent height h1 for parallel tunneling,
compared to smaller h2 for antiparallel tunneling. (adapted from Ref. 17)
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Fig. 4 SPSTM with optically pumped GaAs tip setup.
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Fig.5 (a) Topography image; (b) intensity modulation
image; (c) polarization modulation response image. These 1x1 mm2
images were recorded at the same sample location. (a) & (c)
are simultaneous. (d) 1x1 mm2
MFM image obtained on a typical sample with 10 nm gold-covered
layer.
(adapted from Ref. 24) |
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