A quantum multi-critical point in CeCu6−xAux

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Date
2006-11-15
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier B. V.
Abstract
CeCu6−xAux is a well-known heavy-fermion system in which the ground state is antiferromagnetically ordered for x>0.1 and temperatures below 1 K. Non-Fermi liquid behaviour occurs around this critical concentration. The parent compound, CeCu6, exhibits a structural phase transition near 230 K, where it changes from the Pnma orthorhombic room-temperature structure to the P21/c monoclinic structure. The monoclinicity increases as temperature falls, with β reaching 91.44° at 10 K. In the work presented here, powder neutron diffraction is used to explore the monoclinicity at 8 K as a function of composition for 0.0<x<0.08, just short of the critical concentration. Extrapolation of the square of the monoclinic strain, (ac cosβ)2, suggests that the distortion vanishes at x=0.13. A reanalysis of single-crystal diffraction data on the magnetically ordered side of the phase diagram, x>0.1, indicates that long-range order disappears at exactly the same critical concentration. At a minimum, the structural distortion and antiferromagnetism seem to be competing with each other, and this raises the intriguing possibility that lattice degrees of freedom are important in the non-Fermi liquid regime.
Description
Physical copy held by ANSTO Library at DDC 539.7213/3. Part I
Keywords
Crystal lattices, Crystal structure, Diffraction, Dimensionless numbers, Electrodynamics, Energy levels, Magnetism, Quantum field theory, Rare earth alloys, Scattering
Citation
Robinson, R. A., Goossens, D. J., Torikachvili, M. S., Kakurai, K., & Okumura, H. (2006). A quantum multi-critical point in CeCu6−xAux. Paper presented at the Eighth International Conference on Neutron Scattering (ICNS 2005), "Neutrons for structure and dynamics - a new era", Sydney, Australia, 27 November to 2 December 2005. In Campbell, S. J., Cadogan, J. M., Furusaka, M., Hauser, N., & James, M. (Eds), Physica B: Condensed Matter, 385-386(Part 1), 38-40. doi:10.1016/j.physb.2006.05.095