Berlin 2005 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 35: Correlated Electrons - Quantum Critical Phenomena

TT 35.5: Vortrag

Mittwoch, 9. März 2005, 12:15–12:30, TU H104

Field-tuned Quantum Critical Point in Antiferromagnetic Metals — •Inga Fischer and Achim Rosch — Institut für theoretische Physik, Universität zu Köln

A magnetic field applied to an antiferromagnetic metal can destroy the long-range order and thereby induce a quantum critical point. Such field induced quantum critical behaviour is the focus of many recent experiments. We investigate theoretically the quantum critical behavior of clean antiferromagnetic metals subject to a static, spatially uniform, external magnetic field. The external field is not only a means for tuning the control parameter, it also influences the dynamics of the order parameter by inducing spin precession. This is described by an exactly marginal operator in the spin-fluctuation theory put forward by Hertz. We investigate how the interplay of precession and damping determines the correlation length, specific heat, magnetocaloric effect, and scattering rate. While critical exponents remain the same, the universal scaling functions are modified and even the sign of leading corrections e.g. to the specific heat can be changed.