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Charge ordering in the rare-earth manganates: the origin of the extraordinary sensitivity to the average radius of the A-site cations, 〈rA〉

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dc.contributor.author Arulraj, A
dc.contributor.author Santhosh, P N
dc.contributor.author Gopalan, R S
dc.contributor.author Guha, A
dc.contributor.author Raychaudhuri, A K
dc.contributor.author Kumar, N
dc.contributor.author Rao, C N R
dc.date.accessioned 2012-11-23T11:07:40Z
dc.date.available 2012-11-23T11:07:40Z
dc.date.issued 1998-09-28
dc.identifier 0953-8984 en_US
dc.identifier.citation Journal Of Physics :Condensed Matter 10(38), 8497-8504 (1998) en_US
dc.identifier.uri https://libjncir.jncasr.ac.in/xmlui/10572/1063
dc.description Restricted Access en_US
dc.description.abstract The charge ordering in Nd0.5Sr0.5MnO3 (〈rA〉 = 1.24 Å), which occurs on cooling the ferromagnetic metallic ground state, is readily destroyed on application of a magnetic field of 6 T. For Y0.5Ca0.5MnO3 (〈rA〉 = 1.13 Å), for which the ground state is charge ordered, on the other hand, magnetic fields have no effect on the charge ordering. In order to understand such a marked difference in charge-ordering behaviour of the manganates, we have investigated the structure as well as the electrical and magnetic properties of Ln(0.5)Ca(0.5)MnO(3) compositions (Ln = Nd, Sm, Gd and Dy) wherein 〈rA〉 varies over the range 1.17-1.13 Å. The lattice distortion index, D, and charge-ordering transition temperature, TCO, for the manganates increase with the decreasing 〈rA〉. The charge-ordered state is transformed to a metallic state on applying a magnetic field of 6 T in the case of Nd0.5Ca0.5MnO3 (〈rA〉 = 1.17 Å), but this is not the case with the analogous Sm, Gd and Dy manganates with 〈rA〉 less than 1.17 A. In order to explain this behaviour, we have examined the 〈rA〉-dependence of the Mn-O-Mn bond angle, the average Mn-O distance and the apparent one-electron bandwidth, obtained from these structural parameters. It is suggested that the extraordinary sensitivity of the charge ordering to 〈rA〉 arises From factors other than those based on the Mn-O-Mn bond angle and average Mn-O distances alone. It is possible that the competition between the covalent mixing of the oxygen O: 2p sigma orbital with the A-site and B-sire cation orbitals plays a crucial role. Strain effects due to size mismatch between A-site cations could also cause considerable changes in TCO. en_US
dc.description.uri http://dx.doi.org/10.1088/0953-8984/10/38/010 en_US
dc.language.iso en en_US
dc.publisher IOP Publishing Ltd en_US
dc.rights © 1998 IOP Publishing Ltd en_US
dc.subject Giant Magnetoresistance en_US
dc.subject La1-Xcaxmno3 en_US
dc.subject Diffraction en_US
dc.subject Manganites en_US
dc.subject Transition en_US
dc.subject Pressure en_US
dc.subject Size en_US
dc.title Charge ordering in the rare-earth manganates: the origin of the extraordinary sensitivity to the average radius of the A-site cations, 〈rA〉 en_US
dc.type Article en_US


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