The influence of Magnetic Inhomogeneous State on Thermopower and Magnetothermopower in Sm0.55Sr0.45MnO3 Manganitesстатья
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Дата последнего поиска статьи во внешних источниках: 27 мая 2015 г.
Аннотация:Thermopower alfa and magnetothermopower delta alfa were studied in the single-crystal Sm0.55Sr0.45MnO3 sample, containing clusters of following three types: ferromagnetic clusters with the Curie temperature Tc=134 K, A-type antiferromagnetic clusters with the Neel temperature TNA <= Tc and CE-type antiferromagnetic clusters with the TNCE = 240 K. Temperature dependence of alfa and delta alfa/alfa have extrema in the TNCE-region: large maximum on alfa(T} and sharp minimum on {delta alfa/alfa}(T). Negative magnetothermopower in minimum achieves the giant value 50% in magnetic field H=13,2 kOe. As will be shown delow thermopower is essentially caused by the presence of CE-type antiferromagnetic clusters, in which exists charge-orbital order (CO), displacing oxygen ions. Modified crystalline lattice inside clusters causes change of thermopower in them. This thermopower influences on the voltage drop on sample at measurement of thermopower and, consequency, on the effective value alfa of the whole sample. Enclosure of the magnetic field in the TNCE, which accelerates the destruction of the CE-type antiferromagnetic order, caused sharp decrease of total thermopower. This means that the CE-type antiferromsgnetic clusters with CO order are have main contribution to the thermopower of the whole sample.