R. J. Celotta

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We have constructed a magneto-optical trap for chromium atoms. Using trapping light at 425 nm and two repumping lasers tuned to intercombination transitions, over 10 atoms were trapped and average densities of over 10 m were obtained. Non-exponential loss of atoms is observed at high densities indicating inelastic collisions between trapped atoms. Over a(More)
The magnetic ordering and the interlayer exchange coupling in Mn and Fe/Mn wedge structures grown epitaxially on Fe(001) whisker substrates were investigated using scanning electron microscopy with polarization analysis (SEMPA). In bare Mn/Fe(001) samples, the magnetization of the top Mn layer is collinear with the Fe magnetization, and oscillates between(More)
Through the use of light forces exerted by near-resonant laser light, chromium atoms are focused as they deposit onto a substrate, forming nanometer-scale structures on the surface. The laser light is in the form of a standing wave, in which each node acts as an atom-optical "lens." The result is a highly accurate array of lines with a periodicity of /2 =(More)
Nanostructured materials and devices will play an important role in a variety of future technologies, including magnetics. We describe a method for nanostructure fabrication based on the use of laser light to focus neutral atoms. The method uses neither a mask nor a resist, but relies on the direct deposition of atoms to form permanent structures. Since the(More)
We measure, as a function of interlayer thickness, the magnitude of the bilinear exchange coupling in an Fe/Au/Fe tri-layer, to investigate the existing order of magnitude discrepancy between theory and experiment. We use Fe whisker substrates, scanning electron microscopy with polarization analysis and reflection high energy electron diffraction to monitor(More)
Laser-focusing of atoms has emerged as a viable form of nanofabrication. Structures are formed by focusing chromium atoms as they deposit onto a surface. The focusing occurs in a standing-wave laser field in one or two dimensions, resulting in arrays spaced at exactly half the laser wavelength ( /2 = 212.78 nm). Atomic force, scanning electron, and(More)
The temperature dependence of the short period oscillatory coupling in Fe/Cr/Fe(001) whisker trilayers, when analyzed in light of recent theory, provides strong evidence that incommensurate spin density wave antiferromagnetic order is induced in the Cr over a wide range of thickness and up to temperatures at least 1.8 times the Néel temperature of bulk Cr.(More)
Meaningful tests of theoretical predictions of magnetic multilayer properties require the fabrication of multilayers with nearly the same atomic scale precision as the theoretical models. Multilayers grown epitaxially on single crystal Fe whisker substrates come very close to this ideal standard. We have investigated the growth, magnetic structure, and(More)