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TT: Tiefe Temperaturen

TT 19: Correlated Electrons: Low-dimensional Materials

TT 19.12: Talk

Tuesday, March 28, 2006, 17:00–17:15, HSZ 301

Stripe Correlations in Na_0.75CoO₂ — •Jochen Geck¹, Martin von Zimmermann², Helmuth Berger³, Sergey Borisenko¹, Helmut Eschrig¹, Klaus Koepernik¹, Martin Knupfer¹, and Bernd Büchner¹ — ¹IFW Dresden, Germany — ²HASYLAB at DESY, Germany — ³EPF Lausanne, Switzerland

Spin and charge stripes in correlated two-dimensional electron systems are one of the hot spots of today’s condensed matter research. So far, stripes have been observed in materials based on square lattices like the nickelates and the high-temperature superconducting cuprates. Here we show, based on high-energy x-ray diffraction data and LDA calculations, that sodium-density stripes are formed in Na_0.75CoO₂; a material based on a triangular lattice. The LDA calculations show that the sodium order results in a sizeable dip of the density of states at the Fermi level, pointing to band structure effects as a driving force for the ordering. This indicates that the stripe order is an intrinsic feature of the two-dimensional CoO₂-layers. Similarities regarding the pinning of stripe correlations in the high-temperature superconducting cuprates and the Na_xCoO₂-materials will also be discussed.