Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 7: Superconductivity & Solids At Low Temperature - Poster Session
TT 7.24: Poster
Montag, 27. März 2006, 14:00–17:45, P1
Theory of the in-plane anisotropy of magnetic excitations in YBCO — •Hiroyuki Yamase and Walter Metzner — Max-Planck-Institute for Solid State Research, Heisenbergstrasse 1, D-70569, Stuttgart, Germany
A pronounced xy-anisotropy was observed in recent neutron scattering experiments for magnetic excitations in untwinned YBCO.[1] The relatively small anisotropy of the bare band structure due to the orthorhombic crystal symmetry seems to be enhanced by correlation effects. A natural possibility is that the system is close to a Pomeranchuk instability associated with a d-wave Fermi surface deformation (dFSD).[2,3] We investigate this possibility in the bilayer t-J model within a self-consistent slave-boson mean-field theory. We show that the dFSD correlations drive a pronounced xy-anisotropy of magnetic excitations at low doping and at relatively high temperatures, providing a scenario for the observed xy-anisotropy also in YBCO6.6 and YBCO6.5, and in the pseudogap phase. [1] V. Hinkov et al., Nature 430, 650 (2004). [2] H. Yamase and H. Kohno, J. Phys. Soc. Jpn. 69, 332 (2000); 69 2151 (2000). [3] C. J. Halboth and W. Metzner, Phys. Rev. Lett. 85, 5162 (2000).