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TT: Tiefe Temperaturen

TT 34: Correlated Electrons: Spin Systems and Itinerant Magnets

TT 34.5: Vortrag

Freitag, 31. März 2006, 11:15–11:30, HSZ 301

Helimagnetism and Weak Ferromagnetism in the Edge-Shared Chain Cuprate NaCu₂O₂ — •S.-L. Drechsler¹, J. Richter², A.A. Gippius³, A.N. Vasiliev³, A.A. Bush⁴, A.S. Moskvin⁵, J. Malek⁶, Yu. Prots⁷, W. Schnelle⁷, and H. Rosner⁷ — ¹IFW-Dresden, 01171 Dresden, PF 270116, Germany — ²Universität Magdeburg, Germany — ³Moscow State University, Russia — ⁴Moscow Inst. of Radiotechnics, Electronics and Automation, Russia — ⁵Ural State University Ekaterinburg, Russia — ⁶FZU AVCR, Praha, Czech Rep. — ⁷MPI-cPfS Dresden, Germany

We report on susceptibility, magnetization, ²³Na NMR, and specific heat data of the spin-chain material NaCu₂O₂ in the paramagnetic and ordered phases. Below 13 K, where a sharp field-dependent specific heat peak appears, the NMR lineshape points to an incommensurate static modulation of the local magnetic field consistent with a spiral arrangement of the Cu magnetic moments. At 2 K weak ferromagnetism with a small ordered moment of about 4· 10⁻³µ_B has been observed. LDA based estimates of exchange integrals reveal a large inchain frustration leading to a magnetic spiral.