Münster 1999 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 15: Postersitzung II: Elektronische Eigenschaften (1-12), Josephson-Kontakte (13-27), Heavy Fermions (28-40), Theorie HTSL (41-48), M-I-Überg
änge, Korrelierte Systeme (49-79)

TT 15.43: Poster

Mittwoch, 24. März 1999, 14:30–18:00, Foy

Dynamic nesting and the incommensurate magnetic response in superconducting YBCO . — •Jan Brinckmann^1,2 and P.A. Lee¹ — ¹Massachusetts Institute of Technology, Cambridge, MA, U.S.A. — ²Inst. f. Theorie d. Kondensierten Materie, Uni Karlsruhe

The dynamic magnetic susceptibility χ″ of the t–t′–J-model for YBa₂Cu₃O_6+y compounds is studied in slave-boson mean-field theory. Within a renormalized random-phase approximation χ″ is calculated in wave-vector q space for several fixed energies. At the energy ω₀ of the so-called “41 meV resonance” the magnetic response shows a commensurate peak at the antiferromagnetic wave-vector (π,π) . At somewhat lower energies around ω_inc=0.7ω₀ , however, we find four peaks at q=(π±δ,π) and (π,π±δ) , a pattern previously known from the LSCO family of compounds. Our results are in agreement with inelastic neutron scattering experiments, in particular with the incommensurate response recently observed in YBa₂Cu₃O_6.6 by Mook et.al. We show that dynamic nesting in the dispersion of quasi particles causes this effect.