Structural, Thermal, Magnetic, and Transport Properties of (La2/3Ca1/3)(Mn1-xSnx)O3-δ Compounds |
| J. Przewoźnika, J. Chmista, L. Kolwicz-Chodaka, Z. Tarnawskia, A. Kołodziejczyka, K. Kropa, K. Kellnerb and G. Gritznerb
aFaculty of Physics and Nuclear Techniques, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Cracow, Poland bInstitut für Chemische Technologie Anorganischer Stoffe, Johannes Kepler Universität Linz, 4040 Linz, Austria |
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| The structural, magnetic, and electrical transport properties of Sn-doped manganite La0.67Ca0.33Mn1-x SnxO3-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 TC and the metal-insulator transition temperature TM-I decreased nonlinearly with increasing Sn content. The TC and TM-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 TC 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 TC 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 TC. With increasing Sn content the peak at TC broadened and the area under the peak decreased. For x= 0.03 the peak was hardly detectable. Our results on La0.67Ca0.33 Mn1-xSnxO3 reveal that a small substitution of Sn4+ for Mn4+ suppresses double exchange interactions and strongly affects the magnetic, thermal, and transport properties of the parent compound. |
| DOI: 10.12693/APhysPolA.106.665 PACS numbers: 75.47.Lx, 75.47.Gk, 75.40.Cx |