Spin state of ferric chloride investigated by NMR

Abstract

The spin state of FeCl3 was measured by Nuclear Magnetic Resonance (NMR)as a function of temperature and magnetic field. The sublattice magnetizationobtained from the Fe NMR spectrum fits well with the theoretical predictionfor an antiferromagnet with a magnetic anisotropy field of less than70 mT in the ab-plane. The field dependence of the Fe NMR spectrumshows that a spin rotation plane of helical order starts to align perpendicularlyto the external field direction as the field increases from 0 and endsaround 4 T with no phase transition. From the spin tilting angle analysis, weobtained the quantitative relation among the exchange coupling constants.