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Our magnetic levitation demonstration consists of two parts: A magnetic track and a piece of superconducting
yttrium-barium-copper-oxide (YBCO) with a critical temperature of 93 K (-292 F) cooled by liquid nitrogen.
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The track (Fig. 1) is made up of several hundred individual magnets organized in three parallel rows, oriented such
that the magnetic field is directed up at the center and down at the edges.
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When the superconductors is cooled below the critical temperature in the presence of the track's magnetic field (red
lines), vortices are nucleated in the YBCO (Fig. 2).
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Due to the large degree of imperfections in the YBCO material the vortices are strongly pinned, creating a stable
imprint of the magnetic field (black lines) at the time of cooling (Fig. 3).
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A slight displacement of the superconductor will now lead to a mismatch of the magnetic field and the
"frozen in" vortices, and give rise to a restoring force which seeks to realign the two (Fig. 4).
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The restoring force acts both perpendicular to the track as well as in the vertical direction. Only along the
direction of the track is the magnetic field uniform (Fig. 1) and the superconductor is free to move.
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