In a linear magnetoelectric the lattice is coupled to electric and magnetic fields; both affect the longitudinal-transverse splitting of zone-center optical phonons on equal footing. A response matrix relates the macroscopic fields (D, B) to (E, H) at infrared frequencies. It is shown that the response matrices at frequencies 0 and 1 fulfill a generalized Lyddane-Sachs-Teller relationship. The right-hand side member of such relationship is expressed in terms of weighted averages over the longitudinal and transverse excitations of the medium, and assumes a simple form for a harmonic crystal.
Lyddane-Sachs-Teller Relationship in Linear Magnetoelectrics
Resta;Raffaele
2011
Abstract
In a linear magnetoelectric the lattice is coupled to electric and magnetic fields; both affect the longitudinal-transverse splitting of zone-center optical phonons on equal footing. A response matrix relates the macroscopic fields (D, B) to (E, H) at infrared frequencies. It is shown that the response matrices at frequencies 0 and 1 fulfill a generalized Lyddane-Sachs-Teller relationship. The right-hand side member of such relationship is expressed in terms of weighted averages over the longitudinal and transverse excitations of the medium, and assumes a simple form for a harmonic crystal.File in questo prodotto:
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