Investigation of the dynamic susceptibility of antiferromagnetic MnCO3 near the NMR of Mn55

The real part χ″ of the dynamic magnetic susceptibility of antiferromagnetic MnCO₃ is measured near the NMR of Mn⁵⁵. Two new phenomena are discovered: χ″ vanishes at the unshifted NMR frequency in the region of large dynamic frequency shift (DFS) of NMR, and the NMR line is broadened as the shift varies from large to small values. The results obtained are described satisfactorily by the concept of the DFS of NMR developed in the works of E. A. Turov, M. I. Kurkin, and V. I. Tsifrinovich. Pis’ma Zh. éksp. Teor. Fiz. 64, No. 9, 636–640 (10 November 1996)