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Structural, Thermal, Magnetic, and Transport Properties of (La_{2/3}Ca_{1/3})(Mn_{1-x}Sn_x)O_{3-δ} Compounds

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Przewoźnik J., Chmist J., Kolwicz-Chodak L., Tarnawski Z., Kołodziejczyk A., Krop K., Kellner K., Gritzner G.

Acta Physica Polonica A

2004

vol. 106

issue 5

665-680

The structural, magnetic, and electrical transport properties of Sn-doped manganite La_{0.67}Ca_{0.33}Mn_{1-x} Sn_xO_{3-δ} (x=0, 0.01, 0.03, andδ≈0.06) compounds were studied using X-ray powder diffraction, scanning electron microscopy, AC susceptometer and vibrating sample magnetometer measurements as well as four-probe resistance measurements. The specific heat was measured by the heat-pulse method. The Curie temperature T_C and the metal-insulator transition temperature T_{M-I} decreased nonlinearly with increasing Sn content. The T_C and T_{M-I} values, for the x=0, 0.01, and 0.03 compounds were separated by 18.2 K, 66.3 K, and 10 K, respectively. The resistivity above T_C for all of these compounds followed the Mott variable-range-hopping model. This allowed the estimation of the localization lengths of 2.2Å (x = 0), 1.33Å (x=0.01) and 1.26Å (x=0.03). The x=0 and x=0.01 compounds exhibited anomalies of R(T) at corresponding T_C and allowed the separation of the magnitude of the purely magnetic contribution to the resistance which for x=0 was≈5 .7Ω and for x=0.01,≈22 .4Ω. The specific heat of the Sn-free sample exhibited a sharp peak at T_C. With increasing Sn content the peak at T_C broadened and the area under the peak decreased. For x= 0.03 the peak was hardly detectable. Our results on La_{0.67}Ca_{0.33} Mn_{1-x}Sn_xO_3 reveal that a small substitution of Sn^{4+} for Mn^{4+} suppresses double exchange interactions and strongly affects the magnetic, thermal, and transport properties of the parent compound.

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1 Acta Physica Polonica A

1 2004

1 Chmist J.

1 Gritzner G.

1 Kellner K.

1 Kolwicz-Chodak L.

1 Kołodziejczyk A.

1 Krop K.

1 Przewoźnik J.

1 Tarnawski Z.

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Structural, Thermal, Magnetic, and Transport Properties of (La_{2/3}Ca_{1/3})(Mn_{1-x}Sn_x)O_{3-δ} Compounds