On the structure of the microscopic dielectric tensor in incommensurate crystals |
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Authors: | O S Kushnir L O Lokot |
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Institution: | Physics Department , Lviv National University , Lviv-54 P.O. Box 3154, Lviv, 290054, Ukraine |
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Abstract: | A microscopic model for calculating the optical response of incommensurately modulated phases in insulating crystals is presented. The dominant contribution to the dielectric permittivity tensor is shown to originate from the lowest-index reciprocal lattice vectors, thus proving the validity of the mesoscopic approach developed in several earlier studies. The expression for the mesoscopic Fourier component of the dielectric tensor is obtained. These results may be useful in relation to the controversial problem of the optical activity observed in the incommensurate phases of some A2BX4 family crystals. |
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Keywords: | Insulator Incommensurate phase Dielectric permittivity tensor Microscopic theory |
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