Helical ground state and weak ferromagnetism in the edge-shared chain cuprateS.-L. Drechsler1, J. Richter2, A. A. Gippius3, A. Vasiliev3, A. A. Bush4, A. S. Moskvin5, J. Málek6, Yu. Prots7, W. Schnelle7 and H. Rosner7
1 IFW Dresden - P.O. Box 270116, D-01171 Dresden, Germany
2 Institut für Theoretische Physik, O.-v.-Guericke-Universität Magdeburg - Germany
3 Moscow State University - Russia
4 Moscow Institute of Radiotechnics, Electronics and Automation - Russia
5 Ural State University - Ekaterinburg, Russia
6 Institute of Physics ASCR - Prague, Czech Republic
7 Max-Planck-Institut für Chemische Physik fester Stoffe - Dresden, Germany
received 15 September 2005; accepted 26 October 2005
published online 2 December 2005
We report on susceptibility, magnetization, NMR, and specific heat data of the spin-chain material 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 state of the Cu magnetic moments. At 2 K weak ferromagnetism with an ordered moment of about 4 has been observed. LDA-based estimates of exchange integrals reveal a large inchain frustration leading to a magnetic spiral.
74.72.Jt - Other cuprates, including Tl and Hg-based cuprates.
76.60.-k - Nuclear magnetic resonance and relaxation.
75.10.Pq - Spin chain models.
© EDP Sciences 2005