Preliminary studies of the Raman spectra of \hbox {Ag}_{2}\hbox {Te}\hbox { and }\hbox {Ag}_{5}\hbox {Te}_{3}

The theoretical calculations indicated that the monoclinic low-temperature phase of silver telluride is a new binary topological insulator with highly anisotropic single Dirac cone surface. We obtained crystal ingots containing few grains by the Bridgman method. We also deposited thin films of tellurium, by thermal evaporation method. The Raman spectra of , tellurium and were measured at three excitation wave lengths: 633, 515 and 488 nm. The Raman active modes of , tellurium and are situated at frequencies below 300 while vibrations of other phases appear at higher frequencies.