Metamagnetoelastic and Metamagnetoelectric Behaviour of the Jahn‐Teller Antiferroelastics

It is shown, that the magnetic field induced structural phase transition from the antiferrodistortional to the ferrodistortional phase is possible in Jahn‐Teller antiferroelastics. The phase transition under consideration is simultaneously the crystal transition from the ferroelectric into the antiferroelectric state. The anomalously sharp change of the crystal strain and polarization is realized in the range of the critical magnetic fields. Such a behaviour of crystal strain and polarization is named metamagnetoelasticity and metamagnetoelectricity, respectively. The properties of the ESR spectra of the system under consideration are analysed. The possibilities of experimental observation of the predicted effects are discussed.