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We are developing a promising technique to produce atom chips based on patterned hard magnetic films. Potential advantages compared to the use of current-carrying wire chips include greater flexibility in design, no ohmic heating even for very complicated patterns, no current noise from power supplies, and no stray field from lead wires.
We have found that nano-exchange coupled FePt film is a suitable material. We present two structures designed as Ioffe-Pritchard traps based on in-plane magnetized FePt. The designs are self-biased, the traps exist in the absence of externally applied fields. The first sample was cut by spark erosion out of 40 µm thick foil. With bias field it operates as a mirror-magneto-optical trap. Without bias, it has a single field minimum with calculated trap frequencies of 56 Hz and 5.7 kHz. The second sample was patterned by e-beam lithography and etching into a 250 nm thick film of FePt on Si. It has been designed as an array of 19 Ioffe-Pritchard traps with trap frequencies of 80 kHz radially and 6 kHz axially. Such arrays of microtraps could find application in quantum information processing. |