Browsing by Author "Subramanian, K"

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    A direct two-dimensional comparison of magnetic circular dichroism and magnetic linear dichroism in ultraviolet photoemission spectroscopy
    (American Institute of Physics, 2002-05-13) Gao, XY; Koveshnikov, AN; Madjoe, RH; Subramanian, K; Mankey, GJ; Stockbauer, RL; Kurtz, RL; Louisiana State University System; Louisiana State University; University of Alabama Tuscaloosa
    The angular dependence of magnetic dichroism in photoemission (MDAD) from valence bands is more complicated than that from core levels. It gives access to spin-resolved information about the bands involved in the photoexcitation process. By using a unique ellipsoidal-mirror analyzer, we are able to observe MDAD from valence bands as a two-dimensional image, which gives a direct view of their angular dependence over a large slice through the Brillouin zone. In this work we have investigated Co films grown on a Cu(001) substrate. By using either circularly polarized light or linearly polarized light at a photon energy of 21 eV, magnetic circular dichroism and magnetic linear dichroism (MLD) from the Fermi edge shows different angular dependencies. This is due to the different excitation processes involved with the different light polarizations and it reflects the symmetry of the 3d bands of the Co. Furthermore, we also find that the sign of the MLD can change if differing initial states are involved. First principles calculations of Co bands and their photoelectron angular distributions with the different light polarizations will be presented. This shows that dichroism in valence band photoemission can provide valuable additional information on the electronic and magnetic properties of ultrathin films. (C) 2002 American Institute of Physics.
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    Observation of a bulklike Fermi surface for a monolayer of Ni on Cu(001)
    (American Physical Society, 1997-02-10) Mankey, GJ; Subramanian, K; Stockbauer, RL; Kurtz, RL; Louisiana State University System; Louisiana State University; University of Alabama Tuscaloosa
    We find that the photoelectron angular distributions from the Fermi surface of a monolayer Ni film on Cu are identical to those from thick Ni films and single-crystal Ni(001), and agree well with theoretical predictions for bulk Ni. This bulklike behavior in the monolayer film is attributed to the short screening length of electrons in metals, the similarity of the Ni and Cu cores, and a hybridization between Ni and Cu facilitating an interaction with the underlying crystal field.
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    Video-game controller joystick
    (American Institute of Physics, 1999) Kurtz, RL; Subramanian, K; Mankey, GJ; Louisiana State University System; Louisiana State University; University of Alabama Tuscaloosa
    A method is described to use an inexpensive commercial video-game controller as a joystick for operating stepper-motor controlled manipulators. (C) 1999 American Vacuum Society. [S0734-2101(99)08605-4].