Dresden 2009 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 6: Postersession Correlated Electrons: (General) Theory, Low-Dimensional Systems, Kondo Physics, Heavy Fermions, Quantum-Critical Phenomena
TT 6.64: Poster
Monday, March 23, 2009, 13:00–16:45, P1A
Emergent Lorentz symmetry with vanishing velocity in a critical two-subband quantum wire — •Matthias Sitte1, Achim Rosch1, Julia S. Meyer2, Konstantin A. Matveev3, and Markus Garst1 — 1Institut für Theoretische Physik, Universität zu Köln, Zülpicher Str. 77, 50937 Köln — 2Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA — 3Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
We consider a quantum wire with two subbands of spin-polarized electrons in the presence of strong interactions. We focus on the quantum phase transition when the second subbands starts to get filled. Performing a one-loop renormalization group (RG) analysis of the effective Hamiltonian, we identify the critical theory as a conformal field theory (CFT) of three Majorana fields having an enhanced SU(2) symmetry and central charge c=3/2. While the fixed point is Lorentz invariant, the effective velocities vanish at low energies due to marginally irrelevant operators leading to, e.g., a diverging critical specific heat coefficient. This behavior should occur quite generally in systems where marginally irrelevant terms in the Hamiltonian break Lorentz invariance.
[1] M. Sitte, A. Rosch, J. S. Meyer, K. A. Matveev, and M. Garst, (arXiv:cond-mat/0811.4579).