Regensburg 2004 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 21: Quantenkritische Ph
änomene
TT 21.2: Vortrag
Mittwoch, 10. März 2004, 17:00–17:15, H18
Weak magnetism and non-Fermi liquids near heavy-fermion critical points — •Matthias Vojta1, T. Senthil2, and Subir Sachdev3 — 1Institut für Theorie der Kondensierten Materie, Universität Karlsruhe, D-76128 Karlsruhe — 2Department of Physics, Massachusetts Institute of Technology, Cambridge, USA — 3Department of Physics, Yale University, New Haven, USA
This contribution discusses weak-moment magnetism in heavy-fermion materials and its relation to the non-Fermi liquid physics observed near the transition to the Fermi liquid. We explore the hypothesis that the primary fluctuations responsible for the non-Fermi liquid physics are those associated with the destruction of the large Fermi surface of the Fermi liquid. A concrete realization of this picture is provided by a fractionalized Fermi liquid state which has a small Fermi surface of conduction electrons, but also has other exotic excitations with interactions described by a gauge theory in its deconfined phase. Of particular interest is a three-dimensional fractionalized Fermi liquid with a spinon Fermi surface and a U(1) gauge structure. A direct second-order transition from this state to the conventional Fermi liquid is possible and involves a jump in the electron Fermi surface volume. The critical point displays non-Fermi liquid behavior. A magnetic phase may develop from a spin density wave instability of the spinon Fermi surface. Experimental signatures of this phase and implications for heavy-fermion systems are discussed.