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Charge Ordering In Manganates

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dc.contributor.author Rao, C N R
dc.contributor.author Arulraj, A
dc.contributor.author Santosh, P N
dc.contributor.author Cheetham, A K
dc.date.accessioned 2012-11-21T09:50:01Z
dc.date.available 2012-11-21T09:50:01Z
dc.date.issued 1998-10
dc.identifier 0897-4756 en_US
dc.identifier.citation Chemistry Of Materials 10(10), 2714-2722 (1998) en_US
dc.identifier.uri https://libjncir.jncasr.ac.in/xmlui/10572/1036
dc.description Restricted Access en_US
dc.description.abstract Ordering of Mn3+ and Mn4+ ions occurs in the rare earth manganates of the general composition Ln1-xAxMnO3 (Ln = rare earth, A = Ca, Sr). Such charge-ordering is associated with antiferromagnetic and insulating properties. This phenomenon is to be contrasted with the ferromagnetic metallic behavior that occurs when double-exchange between the Mn3+ and Mn4+ ions predominates. Two distinct types of charge-ordering can be delineated. In one, a ferromagnetic metallic (FMM) state transforms to the charge-ordered (CO) state on cooling. In the other scenario, the CO state is found in the paramagnetic ground state and there is no ferromagnetism down to the lowest temperatures. Magnetic fields transform the CO state to the FMM state, when the average radius of the A-site cations is sufficiently large (<rA> > 1.17 Å). Chemical melting of the CO state by Cr3+ substitution in the Mn site is also found only when <rA> greater than or similar to 1.17 Å. The effect of the size of the A-cations on the Mn- O-Mn angle is not enough to explain the observed variations of the charge-ordering temperature as well as the ferromagnetic Curie temperature Tc. An explanation based on a competition between the Mn and A-cation orbitals for σ-bonding with the oxygen ρσ orbitals is considered to account for the large changes in Tc and hence the true bandwidth, with <rA> Effects of radiation, electric field, and other factors on the CO state are discussed along with charge-ordering in other manganate systems. Complex phase transitions, accompanied by changes in electronic and magnetic properties, occur in manganates with critical values of <rA>or bandwidth. Charge-ordering is found in layered manganates, BixCa1-xMnO3 and CaMnO3-δ . en_US
dc.description.uri http://dx.doi.org/10.1021/cm980318e en_US
dc.language.iso en en_US
dc.publisher American Chemical Society en_US
dc.rights © 1998 American Chemical Society en_US
dc.subject Rare-Earth Manganates en_US
dc.subject Metal-Insulator-Transition en_US
dc.subject A-Site Cations en_US
dc.subject Giant Magnetoresistance en_US
dc.subject Magnetic-Field en_US
dc.subject Neutron-Diffraction en_US
dc.subject Phase-Transition en_US
dc.subject Oxide Systems en_US
dc.subject Perovskite en_US
dc.subject Manganites en_US
dc.title Charge Ordering In Manganates en_US
dc.type Article en_US


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