Universally diverging Grueneisen parameter and magnetocaloric effect close to quantum critical points

  • 16 December 2002
Abstract
Close to a generic quantum critical point, the thermal expansion alpha is much more singular than the specific heat c_p. Consequently, the ``Grueneisen ratio'', Gamma=alpha/c_p, diverges. This property can be used as a highly sensitive probe of quantum critical points. Assuming scaling, we find a Grueneisen ratio Gamma ~ T^(-1/(\nu z)) at the critical pressure p=p_c with non-universal prefactors while Gamma=-G_r/(V_m (p-p_c)) for T -> 0 where V_m is the molar volume and G_r a simple universal combination of critical exponents. In the case of a magnetic-field driven transition, similar relations hold for the magnetocaloric effect (dT/dH)_S. Finally, we determine the corrections to scaling in a class of metallic quantum critical points.

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