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La-139 NMR detection of ferromagnetic clusters far above the Curie temperature in La0.7Ca0.3Fe0.09Mn0.91O3 spin-glass manganite
Tekijät: Matveev VV, Ylinen E, Zakhvalinskii VS, Laiho R
Kustantaja: IOP PUBLISHING LTD
Julkaisuvuosi: 2007
Lehti:: Journal of Physics: Condensed Matter
Tietokannassa oleva lehden nimi: JOURNAL OF PHYSICS-CONDENSED MATTER
Lehden akronyymi: J PHYS-CONDENS MAT
Vuosikerta: 19
Numero: 22
Sivujen määrä: 6
ISSN: 0953-8984
DOI: https://doi.org/10.1088/0953-8984/19/22/226209
Tiivistelmä
The dependence of the La-139 nuclear magnetic resonance (NMR) spin- echo signal on temperature and on the power of the applied radio- frequency pulse is investigated in zero applied magnetic field in La0.7Ca0.3Fe0.09Mn0.91O3 (LCFMO) with Curie temperature (TC) of about 125 K. Plots of the spin-echo signal versus the NMR pulse power reveal two maxima, out of which the high-power component is observed up to temperatures above TC. It is also found that while the temperature dependence of the NMR signal amplitude follows the value of static magnetization M(T-C), the NMR frequency, which is related to the local field at La positions, decreases only slowly and the La-139 NMR signal is preserved at least to 220 K. These results confirm the existence of large ferromagnetic clusters with long life- times above TC in LCFMO.
The dependence of the La-139 nuclear magnetic resonance (NMR) spin- echo signal on temperature and on the power of the applied radio- frequency pulse is investigated in zero applied magnetic field in La0.7Ca0.3Fe0.09Mn0.91O3 (LCFMO) with Curie temperature (TC) of about 125 K. Plots of the spin-echo signal versus the NMR pulse power reveal two maxima, out of which the high-power component is observed up to temperatures above TC. It is also found that while the temperature dependence of the NMR signal amplitude follows the value of static magnetization M(T-C), the NMR frequency, which is related to the local field at La positions, decreases only slowly and the La-139 NMR signal is preserved at least to 220 K. These results confirm the existence of large ferromagnetic clusters with long life- times above TC in LCFMO.
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