ИСТИНА

Low-dimensional magnets are in the focus on present-day studies of quantum spin phenomena and strongly correlated electronic systems. The diversity of inorganic transition-metal compounds leads to a variety of possible spin lattices and coupling regimes, thus allowing for an experimental test of different theoretical models. In this contribution, we explore Cu2+ selenate(IV) chlorides as potential low-dimensional magnets. Here, Cu2+ is a magnetic ion with spin-1/2, while Se4+ forms SeO3 trigonal pyramids that are prone to the formation of peculiar crystal structures. We have succeeded in the preparation of (M/Cu)3(SeO3)2Cl2 M = Ca [1], Sr [2], Pb compounds and studied their crystal structures along with the magnetic behaviour. Magnetic properties were explored by magnetic susceptibility measurements in static fields up to 5 T and by high-field magnetization measurements in pulsed fields up to 60 T. All compounds reveal low-dimensional magnetic behaviour. The susceptibility data are consistent with the spin-dimer model for SrCu2(SeO3)2Cl2 and the spin-chain model for Sr2Cu(SeO3)2Cl2 and CaCu2(SeO3)2Cl2. The differences in the magnetic behaviour can be well understood, if the connectivity of the magnetic Cu2+ sites is considered in terms of planar CuOxCly plaquette units. This assumption is well justified microscopically, because only four ligand atoms contribute to the half-filled, magnetic dx2y2 orbital of Cu2+. The work was supported by RFBR project 12-03-00665-а References [1] O. Janson, A. A. Tsirlin, E. S. Osipova, et al // Phys. Rev. B 83, (2011) 144423 . [2] P.S. Berdonosov, A.V. Olenev, V.A. Dolgikh // J. Solid State Chem. 182 (2009) 2368-2373