DPG Phi
Verhandlungen
Verhandlungen
DPG

Dresden 2003 – scientific programme

Parts | Days | Selection | Search | Downloads | Help

TT: Tiefe Temperaturen

TT 4: Schwere Fermionen, Kondo-Systeme

TT 4.3: Talk

Monday, March 24, 2003, 15:15–15:30, HSZ03

Universally diverging Grüneisen ratio and magnetocaloric effect close to quantum critical points — •Markus Garst1, Lijun Zhu2, Qimiao Si2, and Achim Rosch11Institut für Theorie der Kondensierten Materie, Universität Karlsruhe, 76128 Karlsruhe — 2Department of Physics & Astronomy, Rice University, Houston, TX 77005 1892, USA

We show that close to a generic quantum critical point the thermal expansion α is much more singular than the specific heat cp. Consequently, the Grüneisen ratio Γ = α/cp diverges. With the help of a scaling analysis we find that for T → 0 the Grüneisen ratio behaves universally like Γ = − Gr/Vm (ppc) where Vm is the molar volume and Gr is a simple combination of critical exponents. At the critical pressure p=pc it diverges like Γ ∼ T1/(ν z) with a non-universal prefactor. Furthermore, we have determined the leading contribution to α and cp and discuss corrections to scaling. In case of a magnetic-field driven quantum critical point the magnetocaloric effect plays the role of the Grüneisen ratio. The quantity ΓH = −1/TT/∂ H |S diverges universally upon approaching the quantum critical point for T → 0 as ΓH = − Gr/HHc. Due to their singular behaviour the Grüneisen parameter and the magnetocaloric effect are very sensitive tools to investigate quantum criticality.

100% | Mobile Layout | Deutsche Version | Contact/Imprint/Privacy
DPG-Physik > DPG-Verhandlungen > 2003 > Dresden