Colossal Room-Temperature Magnetoresistance in Thin La(1-x)AgyMnO3 Epitaxial Filmsстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Местоположение издательства:Road Town, United Kingdom
Первая страница:2287
Последняя страница:2291
Аннотация:The first thin La(1-x)AsyMnO3 epitaxial films (y<=x) were grown on SiTiO3 (110) substrates with silver present in the ionized state (Ag^+) only. The Curie temperature Tc of the compositions with x=y=0.05, x=y=0.1, and x=0.3 and y=0.27 crystallizing in the hexagonal structure R3c lie above or close to room temperature. The temperature dependences of electrical ressistivity and of magnetoresistance pass through maxima near Tc, with the magnetoresistance being negative and reaching colossal values of 7-20% in magnetic field H=8.2 kOe not only at Tc but also at room temperature. The magnetic moment per formula unit as derived from the saturation magnetization at T=5 K is substantially smaller than expected for complete ferromagnetic ordering. The magnetization in fields of up to 6 kOe depends on the actual sample cooling condition, and the hysteresis loop of a field-cooled sample is displaced along the H axis by delta H. The above properties can be accounted for by the fact that the films are in a two-phase magnetic (ferromagnetic-antiferromagnetic) state induced by strong s-d exchange. The maximum value of delta H was used to calculate the energy of exchange coupling between the ferromagnetic and antiferromagnetic parts of a sample.