Balz, C.; Lake, B.; Reehuis, M.; Islam, A.T.M.N.; Prokhnenko, O.; Singh, Y.; Pattison, P.; Toth, S.: Crystal growth, structure and magnetic properties of Ca10Cr7O28. Journal of Physics / Condensed Matter 29 (2017), p. 225802/1-9
10.1088/1361-648X/aa68eb
Open Accesn Version

Abstract:
A detailed diffraction study of Ca10Cr7O28 is presented which adds significant new insights into the structural and magnetic properties of this compound. A new crystal structure type was used, where the a and b axes are doubled compared to previous models providing a more plausible structure, where all crystallographic sites are fully occupied. The presence of two different valences of chromium was verified and the locations of the magnetic Cr5+ and nonmagnetic Cr6+ ions were identified. The Cr5+ ions have spin-1/2 and form distorted kagome bilayers which are stacked in an ABC arrangement along the c axis. These results lay the foundation for understanding of the quantum spin liquid behavior in Ca10Cr7O28 which has recently been reported in Balz et al. (2016 Nat. Phys. 12 942).