ANTIFERROMAGNETIC-RESONANCE IN KNIXMN1-XF3 CRYSTALS

The X-band AFMR spectra of single crystals of the series KNixMn1-xF3 h ave been measured over the range of temperatures from 4.2 K to T-N. Th e results lead to the following conclusions: (i) for x < 0.1, transiti on into a weak ferromagnetic phase, characteristic of KMnF3 is maintai ned, (ii) with increasing concentration of nickel ions, the temperatur e range over which the observation of the X-band AFMR is feasible beco mes progressively narrow, and (iii) a considerable widening of the res onance lines and a simultaneous decrease in their amplitude are due to both the relaxation processes and the domain spin-flop effect occurri ng at relatively low external magnetic fields.