Dresden 2011 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 44: Poster Session Correlated Electrons

TT 44.13: Poster

Donnerstag, 17. März 2011, 10:00–13:00, P1

Tuning the magnetism in YbRh₂Si₂ via isoelectronic transition metal (Co, Ir) substitutions: a ⁵⁹Co- and ²⁹Si-NMR study — •Michael Baenitz, Cornelius Krellner, Panchanana Khuntia, Christoph Geibel, and Frank Steglich — Max-Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany.

YbRh₂Si₂ is unique among heavy fermion systems because of its proximity to a quantum critical point (QCP) in the Doniach-type phase diagram. Pronounced non-Fermi-liquid (NFL) behavior was observed. ESR as well as the ²⁹Si-NMR spin-lattice relaxation (SLR) gave strong evidence that the NFL behavior is closely related to the presence of strong ferromagnetic fluctuations competing with antiferromagnetic ones [1,2]. Here we present a ⁵⁹Co- and ²⁹Si-NMR study on the x=0, 0.07, 0.12 and 1 samples of the Yb(Rh_1−xCo_x)₂Si₂ alloy together with ²⁹Si-NMR results on the pure YbIr₂Si₂.The isoelectronic substitution of the smaller Co ion on the Rh site promotes the AF order whereas the substitution of the larger Ir ion strengthen the Kondo interaction. As a consequence the SLRs ²⁹(1/T₁) as well as the spin-spin relaxation rates ²⁹(1/T₂) are damped for the YbIr₂Si₂ system, which allows to study the ²⁹Si-NMR in great detail up to room temperature.
Phys. Rev. Lett. 91, 156401 (2003)
Phys. Rev. Lett. 89, 1072021 (2002)