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arXiv · 0804.2101

Effects of dilution on magnetic and transport properties of La0.7Ca0.3Mn1-xM'xO3

D. N. H. Nam·H. S. Hong·N. V. Khien·N. V. Dai·T. D. Thanh·L. T. C. Tuong·L. V. Hong·N. X. Phuc
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Abstract

Magnetic and transport properties of La0.7Ca0.3Mn1-xM'xO3 (M'=Al,Ti) are studied. The dilution of the Mn lattice results in a weakening of the ferromagnetism, a deterioration of the metallic conductivity, and a strong enhancement of the magnetoresistance. Although Tc linearly decreases with x in the low substitution ranges for both M' series, the scaling behavior Tc(np) previously observed for La0.7Sr0.3Mn1-xM'xO3 [Phys. Rev. B 73, 184403 (2006)] is no longer obtained. Extrapolations of the Tc(np) linear curves to Tc=0 give np values much smaller than 1. These results suggest that, according to a molecular-field approximation, antiferromagnetic superexchange between Mn ions is significant in La0.7Ca0.3MnO3, in contrast to what observed in La0.7Sr0.3MnO3. Additionally, structural data of the Al-substituted samples suggest that variations of the eg-electron bandwidth W cannot explain the decrease of Tc in magnetically diluted manganites.

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D. N. H. Nam, H. S. Hong, N. V. Khien, N. V. Dai, T. D. Thanh, L. T. C. Tuong, L. V. Hong, N. X. Phuc. 2008-04-14. Effects of dilution on magnetic and transport properties of La0.7Ca0.3Mn1-xM'xO3. https://arxiv.org/abs/0804.2101

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