Research Papers in Physics and Astronomy


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Published in Mat. Res. Soc. Symp. Proc. Vol. 672. © 2001 Materials Research Society. Permission to use.


We have observed a distinct surface phase transition for an important class of colossal magnetoresistive materials, La0.65D0.35MnO3 (with D = Sr, Pb) occurring in a surface layer compositionally different from the bulk. The surface phase transition occurs around 240 K compared to 350 K for the bulk and is fundamentally different. In the bulk, a ferromagnetic metal to paramagnetic ‘bad metal’ occurs, while the lower-temperature surface transition is from an n-type (in case of La0.65Sr0.35MnO3) or a p-type (in case of La0.65Pb0.35MnO3) semiconductor to a semimetal with increasing temperature.

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