Electrical & Computer Engineering Research Works

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Author: search.filters.author.Chung, S. H.

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    Low temperature behavior of magnetic domains observed using a magnetic force microscope
    (American Institute of Physics, 2001-06-01) Chung, S. H.; Shinde, S. R.; Ogale, S. B.; Venkatesan, T.; Greene, R. L.; Dreyer, M.; Gomez, R. D.
    A commercial atomic force microscope/magnetic force microscope ~MFM! was modified to cool magnetic samples down to around 100 K under a high vacuum while maintaining its routine imaging functionality. MFM images of a 120 nm thick La0.7Ca0.3MnO3 film on a LaAlO3 substrate at low temperature show the paramagnetic-to-ferromagnetic phase transition. Evolution of magnetic domains and magnetic ripples with decreasing temperature are also observed near the edge of a 20 nm thick patterned Co film on a Si substrate.
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    Universal Scaling of Ballistic Magnetoresistance in Magnetic Nanocontacts
    (The American Physical Society, 2002-12-31) Chung, S. H.; Munoz, M.; Garcıa, N.; Egelhoff, W. F.; Gomez, R. D.
    We show that ballistic magnetoresistance exhibits universal scaling in atomic or nanometer scale contacts. Plotting the data as conductance, we find that, if the maximum magnetoconductance is normalized to unity and the conductance is scaled with the conductivity of the bulk material, the data fall in a narrow region, independent of the nanocontact materials, for our four data sets and four from the literature. The results agree with a theory that takes into account spin-scattering within a magneticdomain wall.
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    Universal scaling of magnetoconductance in magnetic nanocontacts (Invited)
    (American Institute of Physics, 2003-05-15) Chung, S. H.; Munoz, M.; Garcia, N.; Egelhoff, W. F.; Gomez, R. D.
    We present results of half-metallic ferromagnets formed by atomic nanocontact of CrO2– CrO2 and CrO2–Ni that show as much as 400% magnetoconductance. Analysis of the magnetoconductance versus conductance data for all materials known to exhibit so-called ballistic magnetoresistance strongly suggests that the magnetoconductance of nanocontacts follows universal scaling. If the maximum magnetoconductance is normalized to unity and the conductance is scaled to the resistivity of the material, then all data points fall into a universal curve that is independent of the contact material and the transport mechanism. The analysis was applied to all available magnetoconductance data of magnetic nanocontacts in the literature, and the results agree with theory that takes into account the spin scattering within a magnetic domain wall.