https://doi.org/10.1140/epjb/e2005-00375-0
Intrinsic metastability of low doped manganites: La0.8Ca0.2MnO3 case
1
Department of Physics, Ben Gurion University of the Negev, P.O. Box 653,
84105 Beer Sheva, Israel
2
Moscow State Steel and Alloys Institute, 119991,
Moscow, Russia
Corresponding author: a jung@bgumail.bgu.ac.il
Received:
14
June
2005
Published online:
9
December
2005
Transport properties of phase separated La0.8Ca0.2MnO3 crystals
in the aged highly resistive metastable state were studied. It was found that the
coexistence of different ferromagnetic phases at low temperatures is sensitive to
electric current/field. In a contrast with the previously studied low resistivity
metastable states the high resistivity state exhibits positive magnetoresistance and
significant current dependence of the resistivity even at temperatures much higher
than the Curie temperature. Application of current pulses results in appearance of
zero bias anomaly in the current dependent conductivity. Similarly to the low
resistivity metastable states the memory of the resistivity can be erased only after
heating of the sample to K. After one year storage at room
temperature the La0.8Ca0.2MnO3 samples show clear signatures of aging.
The aged samples spontaneously evolute towards high resistivity states. The results
are discussed in the context of a coexistence of two ferromagnetic phases with
different orbital order and different conductivity. The metallic ferromagnetic phase
seems to be less stable giving rise to the experimentally observed electric field
effects and aging.
PACS: 75.47.Gk – Colossal magnetoresistance / 75.47.Lx – Manganites / 71.30.+h – Metal-insulator transitions and other electronic transitions
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2005