Origin of the linear term in the pseudo-spin Hamiltonian of compositionally graded ferroelectrics
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This paper is devoted to the microscopic theory of compositionally graded ferroelectrics (CGF). From a simple microscopic picture of CGF we deduce the so called transverse Ising pseudo-spin model. However the Hamiltonian used in recent papers does not contain a linear term in pseudo-spins. We show that for inhomogeneous material it is necessary to modify the Ising Hamiltonian by addition of the linear term in pseudo-spins. This linear term is equivalent to introduction of an external bias field. The influence of long-range forces is discussed.
KeywordsCompositionally graded ferroelectrics Long-range forces Transverse Ising model
This work has been sponsored by the Ministry of Education of Czech Republic (Research Program MSM 0021620835).
- 16.B.A. Strukov, A.P. Levanyuk, Ferroelectric Phenomena in Crystals, §7.2, (Springer, Berlin Heidelberg, New York, 1998)Google Scholar