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 |