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Antiferromagnetic criticality at a heavy-fermion quantum phase transition

Nature Physics volume 5, pages 753757 (2009) | Download Citation

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Abstract

The interpretation of the magnetic phase diagrams of strongly correlated electron systems remains controversial. In particular, the physics of quantum phase transitions, which occur at zero temperature, is still enigmatic. Heavy-fermion compounds are textbook examples of quantum criticality, as doping, or the application of pressure or a magnetic field can lead to a quantum phase transition between a magnetically ordered state and a paramagnetic regime. A central question concerns the microscopic nature of the critical quantum fluctuations. Are they antiferromagnetic or of local origin? Here we demonstrate, using inelastic neutron scattering experiments, that the quantum phase transition in the heavy-fermion system Ce1−xLaxRu2Si2 is controlled by fluctuations of the antiferromagnetic order parameter. At least for this heavy-fermion family, the Hertz–Millis–Moriya spin fluctuation approach seems to be a sound basis for describing the quantum antiferromagnetic–paramagnetic instability.

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Acknowledgements

We acknowledge B. Vettard, J. Prévitali and J. M. Mignot for support during experiments. We also thank P. Haen, F. Lapierre, B. Fåk, H. Yamagami, M. Lavagna, C. Pépin and M. Continentino for useful discussions.

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Affiliations

  1. Service de Physique Statistique, Magnétisme et Supraconductivité, Institut Nanosciences et Cryogénie, Commissariat à l’Energie Atomique, 17 rue des Martyrs, 38054 Grenoble cedex 9, France

    • W. Knafo
    • , S. Raymond
    •  & J. Flouquet
  2. Laboratoire National des Champs Magnétiques Intenses, UPR 3228, CNRS-UPS-INSA-UJF, 143 Avenue de Rangueil, 31400 Toulouse, cedex 4, France

    • W. Knafo
  3. Institut Néel, CNRS/UJF, 25 avenue des Martyrs, BP 166, 38042 Grenoble cedex 9, France

    • P. Lejay

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Contributions

The crystals were grown by P.L., the experiments were carried out by W.K. and S.R. and the analysis was carried out by W.K., S.R. and J.F.

Corresponding author

Correspondence to W. Knafo.

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https://doi.org/10.1038/nphys1374