Cooperative Jahn-Teller distortion in PrO2

Gardiner, C.H., Boothroyd, A.T., Pattison, P., McKelvy, M.J., McIntyre, G.J. and Lister, S.J.S. (2004) Cooperative Jahn-Teller distortion in PrO2. Physical Review B, 70(2), 024415. (doi:10.1103/PhysRevB.70.024415)

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We report neutron diffraction data on single crystal PrO 2 which reveal a cooperative Jahn-Teller distortion at T D = 120 ± 2 K . Below this temperature an internal distortion of the oxygen sublattice causes the unit cell of the crystallographic structure to become doubled along one crystal axis. We discuss several possible models for this structure. The antiferromagnetic structure below T N = 13.5 K is found to consist of two components, one of which shares the same doubled unit cell as the distorted crystallographic structure. We also present measurements of the magnetic susceptibility, the specific heat capacity, and the electrical conductivity of PrO 2 . The susceptibility data show an anomaly at a temperature close to T D . From the specific heat capacity data we deduce that the ground state is doubly degenerate, consistent with a distortion of the cubic local symmetry. We discuss possible mechanisms for this. The conductivity shows an activated behavior with an activation energy E a = 0.262 ± 0.003 eV .

Item Type:Articles
Keywords:Cooperative Jahn-Teller effect, PrO2.
Glasgow Author(s) Enlighten ID:Webster, Dr Carol
Authors: Gardiner, C.H., Boothroyd, A.T., Pattison, P., McKelvy, M.J., McIntyre, G.J., and Lister, S.J.S.
College/School:College of Science and Engineering > School of Computing Science
Journal Name:Physical Review B
Publisher:American Physical Society
ISSN (Online):1550-235X
Published Online:27 July 2004

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