RAMAN SCATTERING OF Dy/Y RARE EARTH SUPERLATTICE

We report the observations of Raman scattering of the TO phonon modes from the different layers in Dy/Y rare earth superlattices. It is found that helical phase lock-in transition at about 50 K in the Dy/Y superlattice is accompanied by the softening of TO phonons from both Dy magnetic layers and Y nonmagnetic layers.     

RAMAN SCATTERING OF α-ET3(ReO4)2 CHARGE-TRANSFER SALT

We describe the results of Haman studies on C=C stretch modes in α-ET₃(ReO₄)₂ charge-transfer salt with the incident laser beam polarised perpendicular and parallel to the large flat face of plate-like crystal. We have assigned central C=C stretch mode at 1454 cm^-1 and ring C=C stretch mode at 1470cm^-1. The change in ring C=C stretch vibration was observed at the metal-insulator transition of α-ET₃(ReO₄)₂ on warming due to the distortion of the ET molecules.     

RAMAN SCATTERING OF α-ET3(ReO4)2 CHARGE-TRANSFER SALT

We describe the results of Haman studies on C=C stretch modes in α-ET₃(ReO₄)₂ charge-transfer salt with the incident laser beam polarised perpendicular and parallel to the large flat face of plate-like crystal. We have assigned central C=C stretch mode at 1454 cm^-1 and ring C=C stretch mode at 1470cm^-1. The change in ring C=C stretch vibration was observed at the metal-insulator transition of α-ET₃(ReO₄)₂ on warming due to the distortion of the ET molecules.     

RAMAN SCATTERING OF ORGANIC CHARGE-TRANSFER SALTS CONTAINING BEDT-TTF CATION

Raman scattering of several organic charge-transfer salts containing BEDT-TTF of ET cation such as κ-ET₂Cu(NCS)₂, β_L-ET₂I₃, α-ET₃Cl₂. 2H₂O, a-ET₃ (ReO₄)₂ and ETFeBr4 were measured and the variations of the frequencies of C=C bonds of ET molecules on charge transfer were observed. It is found that the energy of C=C stretch modes shows a general downward shift upon ionisation of ET molecule. In addition, we have observed the Raman spectra of C=C stretch vibratinns in κ-ET₂Cu(NCS)₂ single crystal on going through T_c(～10.4 K) and found no detectable effect during the superconducting phase transition.