Dynamical Multiferroicity
The Dzyaloshiksii-Moriya interaction leads to an effective polarisation from a static spin spiral; exploiting the duality between electricity and magnetism in Maxwell’s equations, a complementary effect – Dynamical Multiferroicity – is possible.
A static spin-spiral in space can, via the Dzyaloshiksii-Moriya interaction lead to an effective polarisation; by exploiting the duality between electricity and magnetism in Maxwell’s equations, a complementary effect – Dynamical Multiferroicity – is possible. In dynamical multiferroicity, a magnetic moment results from electric dipoles with transverse (rotational) motion:
\[ \mathbf{m} = \lambda \mathbf{p}\times \partial_t \mathbf{p} \]
Dynamical multiferroicity may be either ex ternally induced, e.g.: by excitation with a circularly polarised laser, or inherent. This latter case may occur in a paraelectric material where the net polarisation is zero, but induced magnetic signatures of dynamical multiferroicity may be present due to transverse fluctuations of electric dipoles. Quantum paraelectrics, including strontium titanate, where quantum fluctuations prevent the appearance of ferroelectric order, are prime candidate materials.