Al-Substitution Effects on Physical Properties of the Colossal Magnetoresistance Compouns La0.67ca0.33mno3

We present a detailed study of the polycrystalline perovskite manganites La0.67Ca0.33AlxMn1-xO3 (x = 0, 0.1, 0.15, 0.5) at low temperatures and high magnetic fields, including electrical resistance, magnetization, ac susceptibility. The static magnetic susceptibility was also measured up to 1000 K. All the samples show colossal magnetoresistance behavior and the Curie temperatures decrease with Al doping. The data suggest the presence of correlated magnetic clusters near by the ferromagnetic transition. This appears to be a consequence of the structural and magnetic disorder created by the random distribution of Al atoms.Comment: 13 pages including 5 figure

Electronic structure of Y(CoXNi1-X)(2) compounds

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Magnetic and Electronic Properties of GdNi5−x\text{}_{5-x}Alx\text{}_{x} Intermetallic Compounds

X-ray photoelectron spectroscopy and magnetic susceptibility of GdNi$\text{}_{5}$, GdNi$\text{}_{4}$Al, GdNi$\text{}_{2}$Al$\text{}_{3}$ and GdNiAl$\text{}_{4}$ are reported. The magnetic state of Ni 3d-electrons strongly depends on the crystallographic structure of the compounds, showing spin fluctuations in GdNi$\text{}_{5}$ and GdNi$\text{}_{4}$Al, a similar behavior with that of metallic Ni in GdNi$\text{}_{2}$Al$\text{}_{3}$ and a filled 3d-band in GdNiAl$\text{}_{4}$