Magnetic and electrical properties of La<sub>1−c</sub>Sr<sub>c</sub>Mn<sub>1−x</sub>Ga<sub>x</sub>O<sub>3</sub> manganites
Badelin, A G; Shchepetkin, A A; Estemirova, S Kh; Sorokin, V V; Karpasyuk, V K; Badelin, A G; Astrakhan State University, 414056, Astrakhan, Russia; Shchepetkin, A A; Institute for Metallurgy UB RAS, 620016, Yekaterinburg, Russia; Estemirova, S Kh; Institute for Metallurgy UB RAS, 620016, Yekaterinburg, Russia; Sorokin, V V; Astrakhan State University, 414056, Astrakhan, Russia; Karpasyuk, V K; Astrakhan State University, 414056, Astrakhan, Russia;
Журнал:
Journal of Physics: Conference Series
Дата:
2011-07-06
Аннотация:
The bulk manganites La<sub>1−c</sub>Sr<sub>c</sub>Mn<sub>1−x</sub>Ga<sub>x</sub>O<sub>3</sub> (c0.15; 0.17; 0.19; 0.025≤ x ≤0.125) were prepared by solid state reactions. The regularities of the influence of Ga<sup>3+</sup> and Sr<sup>2+</sup> concentrations on saturation magnetization at different temperatures, Curie point (T<sub>c</sub>), semiconducting-metallic transition and magnetoresistance have been established. It was found that magnetization at 80 K and T<sub>c</sub> rise with c increasing at each fixed value of x, and decrease as a functions of x at fixed c. Absolute value of negative magnetoresistance for some chemical compositions exceeds 80% at low temperatures for magnetic field strength ∼9 kOe. Ga substitution for Mn shifts phase boundary "rhombohedral-orthorhombic structure" to lower value of c, moreover, excess of oxygen content over stoichiometric one promotes the existence of rhombohedral phase at c0.15. Diamagnetic dilution of octahedral sublattice by Ga<sup>3+</sup> ions and cation vacancies induce semiconducting behaviour in rhombohedral phase, even at c0.19. Metallic type of temperature dependence of resistivity observes in appropriate low temperature range in sintered manganites with c0.17; 0.19 only at small x.
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