Nuclear Magnetic Resonance in One-Dimensional Antiferromagnet KCuF₃

Abstract

Perovskite structure fluoride KCuF₃ is a one-dimensional antiferromagnet in which the magnetic coupling is very strong along the c-axis. No detectable magnetic interaction is found along any axis perpendicular to it. The nuclear magnetic resonance shifts of F¹⁹ nuclei both on the a- and c-axes are determined separately from the measurements on the single crystal. From the observed shifts, it is found that the fractions of the unpaired spin on the 2s and 2p orbitals of the F⁻ ions on the c-axis are f_s=0.44% and f_σ=4.93% respectively, whereas the fictitious f_s′ and f_σ′ of the F⁻ ions on the a-axis are 0.16% and 2.34% respectively.