Dependence of Magneto-Impedance on Magnetic States in Manganeses Oxides

In this paper, the complex impedance spectroscopy (CIS) of La_0.67Sr_1.33MnO₄ and La_0.67Sr_0.33MnO₃ were applied to characterize the ac properties below and above Neel temperature and/or Curie temperature, respectively. We demonstrate that the CIS can be sensitively affected by magnetic states on the manganite thin films. Our result provides further understanding of the dielectrics variation during the phase transition from an antiferromagnetic (AFM) insulating phase and/or a ferromagnetic metallic phase to a paramagnetic PM metallic phase. The CIS was analyzed based on an equivalent circuit model. The results imply that the specific feature of impedance can be attributed to the interplay of dielectric relaxations with the magnetic states at an alternative electromagnetic field.