The observation of the contribution of longitudinal susceptibility to the frequency of the soft magnetoresonance mode in SmFeO3

The behavior of the spectrum of the soft magnetoresonance mode in samarium orthoferrite was experimentally and theoretically studied in the region of the Gamma (4) <----> Gamma (24) orientation phase transition induced by an external magnetic field. The special features of this behavior can be expla ined by the relative contributions of interaction between ferrite subsystem s and longitudinal susceptibility. It is also shown that the contribution o f longitudinal susceptibility to the gap of the soft magnetoresonance mode in samarium orthoferrite can also be substantial in low fields; that is, in the vicinity of spontaneous orientation phase transitions. This is explain ed by the occurrence of spontaneous orientation phase transitions in samari um orthoferrite at high temperatures, at which longitudinal susceptibility is comparable in magnitude with transverse susceptibility. (C) 2001 MAIK "N auka/ Interperiodica".