Regensburg 2004 – scientific programme

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TT: Tiefe Temperaturen

TT 21: Quantenkritische Ph
änomene

TT 21.4: Talk

Wednesday, March 10, 2004, 17:30–17:45, H18

On the quantum critical point in Sr₂Ru_1−xTi_xO₄ — •Ralph Werner¹ and Sam T. Carr² — ¹Institut f"ur Theorie der Kondensierten Materie, Universit"at Karlsruhe, 76128 Karlsruhe — ²Condensed Matter Section, The Abdus Salam ICTP, Strada Costiera 11, 34014 Trieste, Italy

Upon doping with 2.5% of Ti on the Ru site Sr₂RuO₄ develops incommensurate static magnetic order which has been attributed to the nesting of the bands that form the α and β Fermi surfaces [1]. We argue that a standard Stoner mechanism modeled by RPA is insufficient to describe the transition. Instead it is proposed that the quantum critical point is driven by a weak-coupling to strong-coupling crossover which in turn is modeled in a non-perturbative manner [2]. The expected dynamical magnetic response is calculated.

[1] M. Braden et al., Phys. Rev. Lett. 88 (2002) 197002

[2] R. Werner and V. J. Emery, Phys. Rev. B 67 (2003) 014504