Hyperfine Interactions of F¹⁹ Nuclei in K₂CuF₄ and KCuF₃ –The Effect of the Unquenched Orbital Moment on F^- Ions–

Abstract

NMR of F 19 nuclei located on the c -axis in the magnetically ordered K 2 CuF 4 and KCuF 3 was studied. A small anisotropic hyperfine field was observed when the electronic moment lies in the c -plane. This field is interpreted as due to the unquenched orbital moment on F - ion which is neglected in usual treatments. The hyperfine interaction arisen from the mixing between d γ and d ε orbitals through the spin orbit interaction was considered based on the molecular orbital model. The fractional electron transfer of the 2p π -bonding was obtained to be 1∼2.5%.