A Surface Insulator-to-Conductor Phase Transition in Colossal Magnetoresistive Manganese Perovskites Thin Films

Authors

C.N. Borca, University of Nebraska-Lincoln
Bo Xu, University of Nebraska-Lincoln
Takashi Komesu, University of Nebraska-LincolnFollow
Hae-Kyung Jeong, University of Nebraska-LincolnFollow
Sy-Hwang Liou, University of Nebraska-LincolnFollow
Peter A. Dowben, University of Nebraska-LincolnFollow

Date of this Version

5-1-2001

Comments

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

Abstract

We have observed a distinct surface phase transition for an important class of colossal magnetoresistive materials, La_0.65D_0.35MnO₃ (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 La_0.65Sr_0.35MnO₃) or a p-type (in case of La_0.65Pb_0.35MnO₃) semiconductor to a semimetal with increasing temperature.