Papers by Keyword: Electroresistance

Abstract: The effects of Ga substitution at Mn site on electroresistance behaviour of La_0.85Ag_0.15MnO₃ compound prepared by solid-state reaction method were investigated. X-ray diffraction (XRD) measurement were recorded at room temperature and refined by employing Rietveld techniques. Ferromagnetic to paramagnetic transitions behaviour have been observed from ac susceptibility results. Resistivity-temperature curve with different applied currents of 1 mA and 5 mA showed metal-insulator, MI transition temperature, T_MI decreased with increased of the applied currents. The increased in applied current caused the maximum resistivity around T_MI to be decreased for both samples indicated increased in charge carrier density which resulting in drop of resistivity, hence, enhanced double exchange mechanism. The electroresistance (ER) effects have been investigated. The result showed that the ER effect increases when Ga is substituted.

Abstract: The electroresistance, ER effect of La_0.85Ag_0.15Mn_1-xMo_xO₃ (x = 0.00 and 0.05) samples prepared using solid method are investigated. The increased of applied current from 5 mA to 10 mA does not change the metal-insulator transition temperature, T_MI for both samples however decreased the resistivity in the temperature region of 50 K – 300 K. Both samples exhibit large ER effect at low temperature region. At T_MI, the ER value is 75.5% (x =0) and decrease to 34.15% (x = 0.05). However, at 300 K, the value of ER increases to 57 % for Mo substituted sample, and the value decreases to 6.4% for the x =0 sample. The enhanced ER effect at 300 K may be due to the growth of conductive filaments under increased applied current. The increase of applied current may perturb the arrangement of magnetic inhomogeneity induced by Mo substitution, result in reduction of resistivity and lead to the observation of ER effect. These findings suggest potential application of La_0.85Ag_0.15Mn_1-xMo_xO₃ (x = 0.05) in spintronic devices.

Abstract: La_0.7Ba_0.3Mn_1-xFe_xO₃ (x = 0 and 0.02) were prepared by using solid state synthesis method to investigate the effect of Fe³⁺ substitution at Mn-site on electrical behaviour and structural properties. An analysis of X-ray diffraction, XRD data using refinement method shown both x = 0 and x = 0.02 samples were in single phased and crystallized in rhombohedral structural with Pnma space group. From ρ vs T curves shown resistivity decreased under increased of applied current of 10 mA to 20 mA for both samples in the temperature range of 20 K-300 K. The larger electroresistance, ER effect observed for x = 0.02 in temperature range of 20 K – 180 K compared to x = 0 sample is suggested due to the development of filamentary conduction path under increased of applied current. It is suggested that Fe substitution enhanced magnetic inhomogeneity which contribute to the growth of formation of conductive path under increased of applied current, lead to increase of ER effect. In the temperature range of 180 K – 300 K, the observed decreased in ER for Fe substituted sample (x = 0.02) is suggested due to the increased of scattering effect and reduction of available hopping site in metallic region and insulating region, respectively. Restriction in the movement of charge carrier had weakened the ER effect for Fe substituted sample. The observed ER effect indicates the compound has a potential for application such as for non-volatile memory elements.

Abstract: Electric-current induced electroresistance effect has been investigated in epitaxial Pr_0.7Sr_0.3MnO₃ thin film grown on the (100) SrTiO₃ substrate. A significant change ~38% in the ratio of the peak resistance at different currents with a current density up to ~3.3×10³ A/cm² was achieved. Such an ER effect is more remarkable in comparing with that reported in other manganite oxides with similar current densities. Compared with that of the as-grown films, the electroresistance of the post-annealed films is smaller, while the ER effect (~14%) is obtained. Although the nature behind such an electroresistance effect has not been well understood, the field tunability of the metal/insulator transition and the electroresistance effect induced by currents might be of potential for various applications such as filed effect devices.