Conţinutul numărului revistei |
Articolul precedent |
Articolul urmator |
127 0 |
SM ISO690:2012 LAIHO, Reino, LISUNOV, Konstantin, LÄHDERANTA, Erkki, PETRENKO, Peter A., SALMINEN, J., STAMOV, Vladimir, ZAKHVALINSKII, Vasilii. Coexistence of ferromagnetic and spin-glass phenomena in La1-xCaxMnO3 (0 ≤ x ≤ 0.4). In: Journal of Physics Condensed Matter, 2000, vol. 12, pp. 5751-5764. ISSN 0953-8984. DOI: https://doi.org/10.1088/0953-8984/12/26/321 |
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Journal of Physics Condensed Matter | ||||||
Volumul 12 / 2000 / ISSN 0953-8984 /ISSNe 1361-648X | ||||||
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DOI:https://doi.org/10.1088/0953-8984/12/26/321 | ||||||
Pag. 5751-5764 | ||||||
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Low-field magnetic properties of ceramic La1-xCaxMnO3 (0 ≤ x ≤ 0.4) are investigated between T = 5 and 310 K. The paramagnetic-ferromagnetic transition is observed in all the samples. The dependence of the Curie temperature, TC, on x is described within a model of spin polarons associated with electronic localization. Critical behaviour of the susceptibility χ-1(T) approx. (T - TC)γ is observed for T > TC, with the critical exponents γ = 1.20 ± 0.05 and γ* = 1.64 ± 0.06 below and above the composition x ≈ 0.18 corresponding to the Mn4+ ion concentration c ≈ 0.23, respectively. For the compound with x = 0.3 no temperature hysteresis of the resistivity is observed in magnetic fields between 0 and 8 T. In all the samples the field-cooled and zero-field-cooled magnetizations deviate below TC, the difference being approximately equal to the thermoremanent magnetization (TRM). Long-time relaxation of TRM in LCMO is observed for time scales up to 104 s. The relaxation rate reaches a maximum near a wait time tW approx. 103 s. The time dependence of TRM can be described with a stretched exponential law, as in spin or cluster glasses in conditions where the observation time is comparable with tW. |
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Cuvinte-cheie Engineering controlled terms Ceramic materials, ferromagnetism, Magnetic fields, magnetic hysteresis, magnetic properties, magnetic susceptibility, magnetization, mathematical models, Paramagnetism, Relaxation processes Engineering uncontrolled terms Lanthanum calcium manganate, Spin polarons, Thermoremanent magnetization Engineering main heading Lanthanum compounds |
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