Dresden 2003 – scientific programme
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MA: Magnetismus
MA 14: Poster: Schichten(1-31), Spinabh.Trsp.(32-47), Exch.Bias(48-54), Spindyn.(55-64), Mikromag.(65-76), Partikel(77-88), Oflmag.(89-92), Spinelektr.(93-98), Elektr.Theo.(99-103), Mikromag+PhasÜ+Aniso.(104-122), MagnMat.(123-134), Messm+Mol-Mag.(135-139), Kondo(140-151)
MA 14.45: Poster
Tuesday, March 25, 2003, 15:15–19:15, Zelt
Large Low Frequency Noise in Doped Manganite Grain Boundary Junctions — •Jan Boris Philipp, Lambert Alff, Achim Marx, and Rudolf Gross — Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Walther-Meissner Str. 8, D-85748 Garching, Germany
In artificial La2/3Ca1/3MnO3 grain boundaries junctions a large two-level tunneling magnetoresistance (TMR) with TMR values up to 300% at 4.2K at low fields has been demonstrated [1]. The charge transport mechanism across the structurally distorted GB region is still discussed controversially. In order to get more insight into the nature of charge transport across the GB, we have performed a systematic analysis of the low frequency 1/f-noise in single GB junctions formed in epitaxial La2/3Ca1/3MnO3 films deposited on SrTiO3 bicrystal substrates. Below the Curie temperature TC the overall 1/f-noise was found to be dominated by the GB. The dependence of the noise on the bias current, temperature and applied magnetic field gives clear evidence that the large amount of 1/f-noise is caused by localized sites with fluctuating magnetization in a heavily disordered GB region [2]. At 4.2K, additional temporally unstable Lorentzian components show up in the noise spectra.
[1] J.B. Philipp, C. Höfener, S. Thienhaus, J. Klein, L. Alff, and R. Gross, Phys. Rev. B 62, Rapid. Com., R9248 (2000).
[2] J.B. Philipp, L. Alff, A. Marx, and R. Gross, Phys. Rev. B 66, xxxx (2002).