Abstract
We present measurements of the thermal conductivity and the thermal expansion of and . In both compounds, a splitting of the multiplet of the ion causes Schottky contributions to . In this contribution arises from a crystal-field splitting, while in it is due to the Nd-Mn exchange coupling. Another consequence of this coupling is a strongly enhanced canting of the Mn moments. The thermal conductivity is greatly suppressed in both compounds. In , the main scattering process is resonant scattering of phonons between different energy levels of the multiplets, whereas the complex magnetism of the Mn ions is of minor importance. In , resonant phonon scattering on the levels dominates at low temperature, while scattering on magnetic excitations becomes important at higher temperature.
- Received 8 March 2007
DOI:https://doi.org/10.1103/PhysRevB.76.094418
©2007 American Physical Society