Elastic soft mode in perovskite-type layer-structure materials
- 1 October 1980
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 22 (7), 3452-3458
- https://doi.org/10.1103/physrevb.22.3452
Abstract
Measurements of the elastic mode in the layer-structure materials Mn and Cd indicate an almost complete softening of this mode in the tetragonal low-temperature phase. We interpret this temperature dependence with a linear coupling of the strain to a soft-order-parameter fluctuation mode. This softening implies that a low-temperature orthorhombic phase not yet observed experimentally has to be taken into account for explaining the corresponding phase transition. Our results further indicate that the strong coupling of the order-parameter fluctuation mode to the acoustic mode prevents the low-temperature orthorhombic phase from becoming stable and, thus, from being observed experimentally.
Keywords
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