Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 67: Correlated Electrons: f-Electron Systems

TT 67.8: Vortrag

Mittwoch, 18. März 2015, 17:00–17:15, H 3005

Momentum-space structure of quasielastic spin fluctuations in Ce3Pd20Si6 — •P. Y. Portnichenko1, A. S. Cameron1, M. A. Surmach1, P. P. Deen2,3, S. Paschen4, A. Prokofiev4, J.-M. Mignot5, A.M. Strydom6, M.T.F. Telling7,8, A. Podlesnyak9, and D. S. Inosov11TU Dresden, Germany — 2ESS, Sweden — 3Univ. of Copenhagen, Denmark — 4Vienna Univ. of Technology, Austria — 5LLB, France — 6Univ. of Johannesburg, South Africa — 7ISIS, UK — 8Univ. of Oxford, UK — 9SNS, USA

Among heavy-fermion metals, Ce3Pd20Si6 is one of the heaviest-electron systems known to date. Using high-resolution neutron spectroscopy, we observed low-energy magnetic scattering from a single crystal of this compound in the paramagnetic state. We investigated its temperature dependence and distribution in Q space. At low temperatures, a quasielastic magnetic response persists with varying intensity all over the Brillouin zone. It forms a broad hump centered at the (111) scattering vector, surrounded by minima of intensity at (002), (220) and equivalent wave vectors. The Q-space structure distinguishes this signal from a simple crystal-field excitation and rather lets us ascribe it to short-range dynamical correlations between the neighboring Ce ions, mediated by the itinerant heavy f-electrons via the RKKY mechanism. Upon heating, the energy width of the signal follows the conventional T1/2 law, Γ(T)=Γ0+AT. The Q-space symmetry of the quasielastic response suggests that it stems from the simple-cubic Ce sublattice occupying the 8c Wyckoff site, whereas the inequivalent 4a site remains magnetically silent.

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