Magnetotransport properties of La0.67Ca0.33MnO 3 with different grain sizes

• Main Authors: Ewe L.S., Hamadneh I., Salama H., Hamid N.A., Halim S.A., Abd-Shukor R.
• Other Authors: 58032789200
• Format: Article
• Published: 2023
• Subjects: Activation energy; Calcium; Charge carriers; Electric resistance; Grain size and shape; Insulation; Lanthanum; Magnetic fields; Manganese; Manganese compounds; Metal insulator transition; Oxide minerals; Perovskite; Density of state; Electrical resistivities; Energy of electrons; Grain sizes; High temperatures; Higher temperatures; Insulator-metal transition temperatures; Inter grains; Jahn-teller distortions; Magneto transports; Magneto-transport properties; Magnetoresistive; Metallic regimes; Small polaron hopping models; Spin tunneling; Temperature curves; Temperature dependences; Variable range hopping models; Zero fields; Curve fitting

The magnetotransport and magnetoresistive (MR) properties of manganese-based La0.67Ca0.33MnO3 perovskite with different grain sizes are reported. The electrical resistivity was measured as a function of temperature in magnetic fields of 0.5 and 1 T. The insulator-metal transition temperature, T IM, shifted to a higher temperature with the application of the magnetic field. In zero field, T IM is almost constant (?271 K) for all samples except for the sample with the largest grain size, where T IM=265 K. The temperature dependence of resistivity was fitted with several equations in the metallic (ferromagnetic) region and the insulating (paramagnetic) region. The density of states at the Fermi level, N(E F), and the activation energy of electron hopping were estimated by fitting the resistivity versus temperature curves. The ?-T 2 curves are nearly linear in the metallic regime, but the ?-T 2.5 curves exhibit a deviation from linearity. The variable range hopping model and small polaron hopping model fit the data well in the high-temperature region, indicating the existence of the Jahn-Teller distortion that localizes the charge carriers. MR was found to increase with an increase in the magnetic field, an effect which is attributed to the intergrain spin tunneling effect. � 2008 Springer-Verlag.