The Study of Excitations in Strong Magnetoelectric Coupling Systems and Multiferroic Materials
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Date
2015-01
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Addis Ababa University
Abstract
Electric charge is not the only possible property for the interaction of atoms or materials with
other elementary excitations. The spin is a fundamental quantum mechanical property inherent
to elementary particles. Atoms are composed of positively charged core and extended cloud
of electrons prone to induce polarizations which in turn complement interactions with external
fields. Multiferroic Magnetoelectrics find new applications in magnetic as well as electric
devices. The coupling of magnetic and electric degrees of freedom offers additional functionalities
arising from the quantum mechanical interactions of the charges,spins and lattice vibrations.
The interactions of magnetic and lattice phenomena are treated to formulate the model Hamiltonian
and analyzed through the double time Green function. The spectrum of excitation is
found to depend on the excitation wave vector and the spectral broadening explains the interaction
that exists between the two domains. The density fluctuations of electromagnetic domains
and the lattice vibration modes can be due to the the exchange interaction and consequently,
explained by the damping Green function. In particular case, the interaction phenomena of
phonons and magnones have been studied in ferroelectric-ferromagnetic multiferroics making
use of the equation of motion method to understand the magnetizations and polarizations which
indicate the cross coupling of magnetic and electric properties(existence of multiple ferroic
orders) opening a new route towards alternating switching for practical applications,and appreciable
results are obtained in broad agreement with experimental findings
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Keywords
Magnetoelectric Coupling Systems