CMR effect and phase separation in La_0.67Ca_0.33MnO_x and La_0.73Ca_0.27MnO₃ epitaxial thin films. (a) A resistivity (ρ) versus magnetic field (H) curve obtained from La_0.67Ca_0.33MnO_x epitaxial thin films grown on LaAlO₃ substrate at 77 K and the MR ratio reaches to 1.27 × 10⁵%. (b) STS images of the local electronic structure of (La, Ca)MnO₃ thin film taken just below T_c in magnetic fields of 0, 0.3, 1, 3, 5, and 9 T (from left to right and top to bottom). Parts of the surface are insulating (light colors), whereas others are metallic (dark colors) or in an intermediate state. The color represents the local differential conductance at a fixed bias of 3 V. Scale bar, 100 nm. (a)Reprinted with permission from Ref. [7]. Copyright 1994, The American Association for the Advancement of Science. (b) Reprinted with permission from Ref. [28]. Copyright 1999, The American Association for the Advancement of Science.