Magnetic properties of the magnetoelectric compound Cu2OSeO3: Magnetization and 77Se NMR study

We present magnetization and77Se Nuclear Magnetic Resonance (NMR) measurements in single crystals of the magneteoelectric compound Cu2OSeO3. The temperature and field dependence of the magnetization suggest a ferrimagnetic ordering at Tc≃ 60 K in a 3up-1down configuration. The easy axis of the magnetization is along the [100] crystallographic direction. The77Se NMR line shape data collected at 14.09 T are consistent with the symmetries imposed by the cubic P213 space group in the temperature range 20-290 K and confirm that the magnetic transition is not accompanied by any lowering of the crystal symmetry as has recently been proposed by Bos et al. [Phys. Rev. B 78 094416 (2008)].