Observation of an antiferromagnetic resonance in the spin-Peierls compound CuGeO3doped with Zn

Abstract
The results of electron-spin-resonance (ESR) measurements on a single crystal of the spin-Peierls compound CuGeO3 doped with 4% Zn are reported. We have observed ESR signals in the antiferromagnetic phase below the Néel temperature (TN=4.2 K). The frequency vs magnetic-field relation of these ESR signals is well explained by the classical theory of antiferromagnetic resonance with orthorhombic anisotropy. The excitation energies at zero field are 26.4 GHz (0.11 meV) and 40.6 GHz (0.17 meV).