Magnetic field-dependent dielectric constant in La2/3Ca1/3MnO3
  We report a rather high dependence of the dielectric permittivity on the magnetic field in La2/3Ca1/3MnO3. The variation is maximum at around 270 K, little above the Curie temperature, TC, and it reaches a 30% under only 0.5 T. We attribute this phenomenon to the space-charge or interfacial polarization produced between the insulator and the metallic regions segregated intrinsically in the material above TC. 
J. Rivas, J. Mira, B. Rivas-Murias, A. Fondado, J. Dec, W. Kleemann,   M. A. Senaris Rodriguez