title: Universally diverging Grüneisen parameter and the magnetocaloric effect close to quantum critical points.
abstract: At a generic quantum critical point, the thermal expansion alpha is more singular than the specific heat c(p). Consequently, the "Grüneisen ratio," Gamma=alpha/c(p), diverges. When scaling applies, Gamma approximately T(-1/(nu z)) at the critical pressure p=p(c), providing a means to measure the scaling dimension of the most relevant operator that pressure couples to; in the alternative limit T-->0 and p not equal p(c), Gamma approximately 1/(p-p(c)) with a prefactor that is, up to the molar volume, a simple universal combination of critical exponents. For a magnetic-field driven transition, similar relations hold for the magnetocaloric effect (1/T) partial differential T/ partial differential H|(S). Finally, we determine the corrections to scaling in a class of metallic quantum critical points.
authors.affiliation: Department of Physics & Astronomy, Rice University, Houston, Texas 77005-1892, USA.
authors.forename: Lijun
authors.initials: L
authors.lastname: Zhu
authors.forename: Markus
authors.initials: M
authors.lastname: Garst
authors.forename: Achim
authors.initials: A
authors.lastname: Rosch
authors.forename: Qimiao
authors.initials: Q
authors.lastname: Si