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APS » Journals » Phys. Rev. Lett. » Volume 94 » Issue 15
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Phys. Rev. Lett. 94, 157203 (2005) [4 pages]

Current Oscillation and Low-Field Colossal Magnetoresistance Effect in Phase-Separated Manganites

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M. Tokunaga*, H. Song, Y. Tokunaga, and T. Tamegai
Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan

Received 9 August 2004; published 21 April 2005

See accompanying Physics Focus

Current-induced switching from a metallic to an insulating state is observed in phase-separated states of (La1-yPry)0.7Ca0.3MnO3 (y=0.7) and Nd0.5Ca0.5Mn1-zCrzO3 (z=0.03) crystals. The application of magnetic fields to this current-induced insulating state causes a pronounced low-field negative magnetoresistance effect [ρ(H)/ρ(0)=10-3 at H=1  kOe]. The application of a constant voltage also causes the breakdown of the Ohmic relation above a threshold voltage. At voltages higher than this threshold value, oscillations in currents are observed. This oscillation is well reproduced by a simple model of local switching of a percolative conduction path.

© 2005 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.94.157203
DOI:
10.1103/PhysRevLett.94.157203
PACS:
75.47.Lx, 64.60.Ak, 64.75.+g, 71.30.+h

*Electronic address: mtokunaga@ap.t.u-tokyo.ac.jp

 
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