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University of Cambridge > Department of Physics. Cavendish Laboratory > Theory of Condensed Matter > CoMePhS |
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Properties of Manganites
What are
Manganites Manganites are materials
which have a perovskite crystal structure.
Perovskites are very common on earths surface and named after Count
Perovski the geologist who first described them. In the general perovskite the red atoms
are usually oxygen, the green and blue atoms are cations called A and B site
cations respectively. The A site
cation is a rare earth element and the B site is an alkaline earth. In a manganite the B site
cations are Mn, so the general formula of a manganite is AMnO3. We have been interested in doped
manganites of the form A1-x Bx MnO3. The amount of doping, x, then controls the
proportions of the elements A and B in the crystal. In particular La1-x Cax MnO3
displays a very rich and varied phase diagram. One of the very important
properties of La1-x Cax
MnO3 is its ability to behave as both an electrical
insulator and a conductor within the same chemically homogenous sample. So although the sample is all of the same
material there is a separation into at least two distinct phases with very
different electrical properties. The
electrical inhomogeneity is an example of electronic soft matter.
From the Cover, Physics
Today, January 2003 |
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