Increase in Tc and spin glass transition in La0.9Ca0.1Mn1−yCryO3 (y=0, 0.1 and 0.2) |
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Authors: | T Sudyoadsuk R Suryanarayanan P Winotai |
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Institution: | a Department of Chemical Physics, Mahidol University, Bangkok 10400, Thailand b Laboratoire de Physico-Chimie de l'Etat Solide, UMR8648, Bât 414 Université Paris-Sud, 91405 Orsay, France |
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Abstract: | We report on the structural, frequency dependent ac susceptibility, dc magnetization and magnetoresistance (MR) measurements on polycrystalline samples of La0.9Ca0.1Mn1−yCryO3 (y=0, 0.1 and 0.2) prepared by sol-gel technique. For y=0, a paramagnetic to ferromagnetic transition is observed at Tc=136 K. Both for y=0.1 and 0.2, Tc increases from 136 to 180 K. For y=0, the imaginary part of the ac susceptibility shows a broad transition at Tf<Tc which does not depend very much on the frequency. However, for y=0.1 and 0.2, the frequency dependence resembles that of a spin glass. Though all the three samples show a semi-conducting behavior between 300 and 5 K, a negative MR is observed corresponding to Tc and Tf. The value of MR decreases for the Cr substituted samples. |
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Keywords: | 75 50 I k 75 47 I x 75 47 G k |
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