Anomalous thermal expansion and strong damping of the thermal conductivity of NdMnO3 and TbMnO3 due to 4f crystal-field excitations

K. Berggold, J. Baier, D. Meier, J. A. Mydosh, T. Lorenz, J. Hemberger, A. Balbashov, N. Aliouane, and D. N. Argyriou
Phys. Rev. B 76, 094418 – Published 26 September 2007

Abstract

We present measurements of the thermal conductivity κ and the thermal expansion α of NdMnO3 and TbMnO3. In both compounds, a splitting of the 4f multiplet of the R3+ ion causes Schottky contributions to α. In TbMnO3 this contribution arises from a crystal-field splitting, while in NdMnO3 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 TbMnO3, the main scattering process is resonant scattering of phonons between different energy levels of the 4f multiplets, whereas the complex 3d magnetism of the Mn ions is of minor importance. In NdMnO3, resonant phonon scattering on the 4f levels dominates at low temperature, while scattering on magnetic excitations becomes important at higher temperature.

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  • Received 8 March 2007

DOI:https://doi.org/10.1103/PhysRevB.76.094418

©2007 American Physical Society

Authors & Affiliations

K. Berggold, J. Baier, D. Meier, J. A. Mydosh, and T. Lorenz

  • II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany

J. Hemberger

  • Experimentalphysik V, Institut für Physik, University of Augsburg, 86135 Augsburg, Germany

A. Balbashov

  • Moscow Power Engineering Institute, 105835 Moscow, Russia

N. Aliouane and D. N. Argyriou

  • Hahn-Meitner-Institut Berlin, Glienicker Strasse 100, 14109 Berlin, Germany

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Issue

Vol. 76, Iss. 9 — 1 September 2007

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