Charge Distribution and Hyperfine Interactions in the CuFeO2 Multiferroic According to 63,65Cu NMR Data

For the first time, the CuFeO 2 single crystal has been studied by 63,65 Cu nuclear magnetic resonance (NMR). The measurements have been carried out in the temperature range of T = 100−350 K in the magnetic field H = 117 kOe applied along different crystallographic directions. The components of the electric field gradient tensor and the hyperfine coupling constants are determined. It is shown that electrons of copper 4 s and 3 d orbitals are involved in the spin polarization transfer Fe → Cu. The occupancies of these orbitals are estimated.