Two-phase character of metallic ferromagnetism in manganites.
(55)Mn NMR spectra of several ferromagnetic manganites, including La(0.7)Ca(0.3)MnO(3) and La(0.7)Sr(0.3) MnO(3), were measured as a function of temperature. A thorough analysis of the spin-spin relaxation and the NMR line shape revealed that in these compounds two different ferromagnetic phases coexist below T(C) in a certain temperature interval which depends on the composition. The phase with lower hyperfine field has faster nuclear relaxation, its characteristic dimension is a few nm, and its volume decreases with decreasing temperature. The NMR lines of both phases are motionally narrowed, i.e., the electron holes are mobile.
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Donetsk Institute of Physics & Technics, Academy of Sciences of Ukraine, Rozy Luxembourg 72, 83114 Donetsk, Ukraine.
Novák
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