Symmetry
Each multiferroic property is closely linked to symmetry. The primary ferroic properties (see table) can be characterized by their behavior under space and time inversion. Space inversion for example will reverse the direction of polarization P while leaving the magnetization M invariant. Time reversal, in turn, will change the sign of M, while the sign of P remains invariant.
| Space invariant | Space variant | |
| Time invariant | Ferroelastic | Ferroelectric |
| Time variant | Ferromagnetic | Ferrotoroidic |
Magnetoelectric multiferroics require simultaneous violation of space and time inversion symmetry. In BiFeO3, for example, off-centering of ions gives rise to an electric polarization, while at a lower temperature additional magnetic ordering breaks time-reversal symmetry.
Read more about this topic: Multiferroics
Famous quotes containing the word symmetry:
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—George Gordon Noel Byron (1788–1824)