Spin Fluctuations in Normal State CeCu2Si2 on Approaching the Quantum Critical Point

Julia Arndt, Oliver Stockert, Karin Schmalzl, Enrico Faulhaber, Hirale S. Jeevan, Christoph Geibel, Wolfgang Schmidt, Michael Loewenhaupt, and Frank Steglich
Phys. Rev. Lett. 106, 246401 – Published 13 June 2011

Abstract

We report on the magnetic excitation spectrum in the normal state of the heavy-fermion superconductor CeCu2Si2 on approaching the quantum critical point (QCP). The magnetic response in the superconducting state is characterized by a transfer of spectral weight to energies above a spin excitation gap. In the normal state, a slowing-down of the quasielastic magnetic response is observed, which conforms to the scaling expected for a QCP of spin-density-wave type. This interpretation is substantiated by an analysis of specific heat data and the momentum dependence of the magnetic excitation spectrum. Our study represents the first direct observation of an almost critical slowing-down of the normal state magnetic response at a QCP when suppressing superconductivity. The results strongly imply that the coupling of Cooper pairs in CeCu2Si2 is mediated by overdamped spin fluctuations.

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  • Received 23 March 2011

DOI:https://doi.org/10.1103/PhysRevLett.106.246401

© 2011 American Physical Society

Authors & Affiliations

Julia Arndt1,*, Oliver Stockert1, Karin Schmalzl2, Enrico Faulhaber3,†, Hirale S. Jeevan1,‡, Christoph Geibel1, Wolfgang Schmidt2, Michael Loewenhaupt3, and Frank Steglich1

  • 1Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Strasse 40, 01187 Dresden, Germany
  • 2Jülich Centre for Neutron Science JCNS, Forschungszentrum Jülich GmbH, Outstation at ILL, 38042 Grenoble, France
  • 3Institut für Festkörperphysik, Technische Universität Dresden, 01062 Dresden, Germany

  • *Present address: Institut für Luft- und Kältetechnik, Dresden, Germany. Julia.Arndt@ilkdresden.de
  • Present address: PANDA, FRM II, Garching, Germany.
  • Present address: I. Physikalisches Institut, Georg-August-Universität Göttingen, Germany.

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Issue

Vol. 106, Iss. 24 — 17 June 2011

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