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TT: Fachverband Tiefe Temperaturen

TT 40: Poster Session Correlated Electrons

TT 40.14: Poster

Mittwoch, 13. März 2013, 15:00–19:00, Poster D

Momentum dependence of the almost quantum critical spin fluctuations in CeCu₂Si₂ — •Zita Huesges¹, Oliver Stockert¹, Hirale S. Jeevan¹, Karin Schmalzl², and Frank Steglich¹ — ¹Max Planck Institute CPfS, Dresden, Germany — ²Jülich Center for Neutron Science, outstation at Institut Laue-Langevin, Grenoble, France

The heavy-fermion superconductor CeCu₂Si₂ is located close to a quantum critical point. The spin fluctuations at the nesting wave vector Q_AF in the normal state are quasielastic and show considerable slowing down. The magnetic response also exhibits scaling expected for a 3D spin-density-wave quatum critical point. We present here the first measurement of the momentum dependence of these almost quantum critical fluctuations. The temperature dependence of the linewidth of the spin fluctuations in reciprocal space is studied and compared to theoretical expectations, which arise from the connection of momentum width and energy width via the dynamical critical exponent z.