Recent publications mention that the magnetic and ferroelectric phases in a multi ferroic material couple through the piezoelectric phase of the ferroelectric. How does that coupling occur if the dielectric is paraelectric and not ferroelectric? Also how would you measure the magnetodielectric coupling constant of a paraelectric/ferrite multiferroic material? Thanks
Dear Somnath Sengupta,
If I consider piezoelectric polarisation or any type of electric polarisation, that orients the electric dipoles in a particular direction.
Magnetism is due to the atomic magnetic moments and their orientation in a lattice.
So, due to the electric polarisation of the material, the electric dipoles are oriented .
This may change the magnetic dipole orientation in the lattice .
Another point is AC effect.
It is obvious that change in electric polarisation, changes electric flux inside as well as outside the material.
So, according to Faraday's Law of induction, there will be an induced magnetic field and hence may cause a magnetisation of the material.
But, all these are general statements.
Electromagnetic coupling can't be discussed without details of the material.
Thanks
N Das
magnetoelectric effect in a given composite is usually characterized by measuring the magnetoelectric coefficient, α = dE/dH where E is electric field and H is the magnetic field. magnetoelectric effect using the dynamic method and also a new method developed in our laboratory which is based on pulsed magnetic fields. https://cimav.repositorioinstitucional.mx/jspui/bitstream/1004/386/1/Magnetoelectric%20Measurements%20by%20Two%20Different%20Methods%20of%20Cobalt%20Ferrite-Barium%20Titanate%20Composites.pdf
Check https://www.science.gov/topicpages/m/magnetoelectric+coupling+coefficient
I am not an expert in multiferroics, but I suppose that an approach to this problem could start via the crystal field phonon coupling, which couples movements of ions (which may produce electric dipole moment) to magnetism. Have a look at publications on this topic and on the possibilities of calculation in McPhase, maybe this helps www.mcphase.de
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