The availability of practical routes to creating multiferroic materials from 2000 the observation that the non-collinear magnetic ordering in orthorhombic TbMnO 3 and TbMn 2 O 5 causes ferroelectricity, and the identification of unusual improper ferroelectricity that is compatible with the coexistence of magnetism in hexagonal manganite YMnO 3.
32.
The cause of such interest is that these crystals can be used as good model objects for the investigation of such key phenomena in solid state physics as quantum tunnelling of atomic particles in solid state, cooperative properties of the system of local centers with internal degrees of freedom, and ferroelectricity.
33.
The PJTE theory of ferroelectricity in ABO3 crystals was expanded to show that, dependent of the number of electrons in the d n shell of the transition metal ion B 4 + and their low spin or high spin arrangement ( which controls the symmetry and spin multiplicity of the ground and PJTE active excited states of the [ BO 6 ] center ), their ferroelectricity may coexist with a magnetic moment ( multiferroicity ).
34.
The PJTE theory of ferroelectricity in ABO3 crystals was expanded to show that, dependent of the number of electrons in the d n shell of the transition metal ion B 4 + and their low spin or high spin arrangement ( which controls the symmetry and spin multiplicity of the ground and PJTE active excited states of the [ BO 6 ] center ), their ferroelectricity may coexist with a magnetic moment ( multiferroicity ).
