Dresden 2006 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 25: Correlated Electrons - Poster Session

TT 25.95: Poster

Mittwoch, 29. März 2006, 14:30–18:30, P1

Magnetic excitations in 214-Ruthenates — •Paul Steffens¹, Olaf Schumann¹, Jörg Baier¹, Markus Kriener¹, Oliver Friedt¹, Yvan Sidis², Jiri Kulda³, Satoru Nakatsuji⁴, Yoshiteru Maeno⁴, and Markus Braden¹ — ¹II. Physikalisches Institut, Universität zu Köln — ²Laboratoire Léon Brillouin, France — ³Institut Laue-Langevin, Grenoble, France — ⁴Kyoto University, Japan

We present investigations of the magnetic excitation spectra of pure and doped Sr₂RuO₄, i.e. Ca_2−xSr_xRuO₄ (0≤x≤2) and Ti-doped Sr₂RuO₄.
In the spin-triplet superconductor Sr₂RuO₄, the excitation spectrum is dominated by incommensurate fluctuations, which are caused by Fermi surface nesting. In addition, a weak ferromagnetic component is observed. Upon Ti-doping, the incommensurate component is enhanced and finally condenses into static order.
Substitution of Sr by Ca leads to a complex phase diagram with different magnetic phases. We report studies on samples with 0.2≤x≤0.6, i.e. a region where metamagnetism is observed and where the behaviour seems to be controlled by the balance between two different types of magnetic instability: an incommensurate and a ferromagnetic one. Our results reveal how the competition between these two is influenced by temperature, magnetic field and chemical composition.