17O NMR Study of the Triangular Lattice Antiferromagnet CuCrO2

The single crystalline and powder samples of multiferroic CuCrO2 have been investigated by O-17 NMR techniques in the paramagnetic and magnetically ordered states. The unusual negative hyperfine field on oxygen nuclei, H-hf = -5.2 kOe/mu B, has been determined in paramagnetic state. The O-17 NMR spectrum in ordered state has a shape typical for incommensurate magnetic structure. It can be well described taking into account only dipole fields which are produced by Cr3+- ions with magnetic moment mu = 2.2 mu(B). The parameters of the EFG (electric field gradient) tensor - the quadrupole frequency (upsilon(Q)) and the asymmetry parameter, have been determined. The value of upsilon(Q) increases monotonously with decreasing temperature in the range 90 K > T > 1.5 K. The estimates of the population of the ligands p - orbitals have been obtained. (C) 2018 Elsevier B.V. All rights reserved.