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Wyświetlanie 1-2 z 2
Tytuł:
Spin and lattice dynamics of La2/3Ca1/3MnO3 doped with 1% 119Sn
Autorzy:
Przewoźnik, J.
Żukrowski, J.
Chmist, J.
Japa, E.
Kołodziejczyk, A.
Krop, K.
Kellner, K.
Gritzner, G.
Powiązania:
https://bibliotekanauki.pl/articles/147199.pdf
Data publikacji:
2004
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
119Sn Mössbauer
LCMO manganites
f-factor
metal-insulator
Opis:
1 at.% 119Sn doped La0.67Ca0.33MnO3 compound was studied by Mössbauer spectroscopy, magnetization, AC susceptibility and resistivity measurements. Huge separation (66 K) of the transition temperatures from the ferromagnetic (FM) to paramagnetic (PM) state (TC) and from metallic to insulating state (TM-I) clearly shows that transition from FM metallic to PM insulator phase goes via FM insulator phase. The Mn lattice dynamics was studied by the relative changes of Lamb-Mössbauer factor f as a function of temperature. In the Debye approximation from the calculated ln(f/f0) values of the characteristic Debye temperatures (čD) were estimated for the FM (368(10) K) and PM (391(6) K) phases. No anomaly of -ln(f/f0) at TM-I and its rather spurious increase around TC was found. The 119Sn isotope as a local diamagnetic probe samples the transferred hyperfine field (Bhf) from its neighbour Mn magnetic moments and witnesses the dynamics of the Mn moments. Theoretical curve based on the molecular field theory was fitted to the experimental values of Bm hf ax and the value of the ordering temperature (TC * H 280 K) of Mn moments inside the large FM domains was estimated. It is much higher than the TC (172 K) obtained from magnetization measurement. The coexistence of FM and PM phases, which is evident from the shape of our 119Sn Mössbauer spectra, was confirmed for temperatures T e 150 K and indicates the inhomogeneous character of the magnetic transition.
Źródło:
Nukleonika; 2004, 49,suppl.3; 37-42
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural, Thermal, Magnetic, and Transport Properties of (La$\text{}_{2}\text{}_{/}\text{}_{3}$ Ca$\text{}_{1}\text{}_{/}\text{}_{3}$ )(Mn$\text{}_{1-x}$Sn$\text{}_{x}$)O$\text{}_{3-δ}$ Compounds
Autorzy:
Przewoźnik, J.
Chmist, J.
Kolwicz-Chodak, L.
Tarnawski, Z.
Kołodziejczyk, A.
Krop, K.
Kellner, K.
Gritzner, G.
Powiązania:
https://bibliotekanauki.pl/articles/2038395.pdf
Data publikacji:
2004-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
75.47.Gk
75.40.Cx
Opis:
The structural, magnetic, and electrical transport properties of Sn-doped manganite La$\text{}_{0.67}$Ca$\text{}_{0.33}$Mn$\text{}_{1-x}$ Sn$\text{}_{x}$O$\text{}_{3-δ}$ (x=0, 0.01, 0.03, andδ≈0.06) compounds were studied using X-ray powder diffraction, scanning electron microscopy, AC susceptometer and vibrating sample magnetometer measurements as well as four-probe resistance measurements. The specific heat was measured by the heat-pulse method. The Curie temperature T$\text{}_{C}$ and the metal-insulator transition temperature T$\text{}_{M-I}$ decreased nonlinearly with increasing Sn content. The T$\text{}_{C}$ and T$\text{}_{M-I}$ values, for the x=0, 0.01, and 0.03 compounds were separated by 18.2 K, 66.3 K, and 10 K, respectively. The resistivity above T$\text{}_{C}$ for all of these compounds followed the Mott variable-range-hopping model. This allowed the estimation of the localization lengths of 2.2Å (x = 0), 1.33Å (x=0.01) and 1.26Å (x=0.03). The x=0 and x=0.01 compounds exhibited anomalies of R(T) at corresponding T$\text{}_{C}$ and allowed the separation of the magnitude of the purely magnetic contribution to the resistance which for x=0 was≈5 .7Ω and for x=0.01,≈22 .4Ω. The specific heat of the Sn-free sample exhibited a sharp peak at T$\text{}_{C}$. With increasing Sn content the peak at T$\text{}_{C}$ broadened and the area under the peak decreased. For x= 0.03 the peak was hardly detectable. Our results on La$\text{}_{0.67}$Ca$\text{}_{0.33}$ Mn$\text{}_{1-x}$Sn$\text{}_{x}$O$\text{}_{3}$ reveal that a small substitution of Sn$\text{}^{4+}$ for Mn$\text{}^{4+}$ suppresses double exchange interactions and strongly affects the magnetic, thermal, and transport properties of the parent compound.
Źródło:
Acta Physica Polonica A; 2004, 106, 5; 665-680
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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