Infrared study of superlattice formation in Ti1+xSe2 |
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Authors: | K.C. Woo F.C. Brown |
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Affiliation: | Department of Physics and Materials Research Laboratory University of Illinois at Urbana-Champaign Urbana, Illinois 61801 USA |
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Abstract: | Infrared reflectivity measurements have been made on two Ti1+xSe2 crystals of different stoichiometry over the range 200 cm?1 to 4000 cm?1 before and after the formation of a 2ao × 2co superlattice. In both crystals at room temperature a heavily damped Drude edge is observed at about 1000 cm?1. At liquid helium temperatures, below the phase transition, the Drude minimum of a non-stoichiometric crystal () is at 750 cm?1 whereas the low temperature minimum of a more stoichiometric sample (Tc = 198 K) is below 350 cm?1. Also, new absorption peaks are seen to develop below Tc at about 3700 cm?1 and 3300 cm?1 for the non- stoichiometric and stoichiometric-crystals respectively. The observed phenomena are related to the energy gaps which open up in the band structure below the phase transition temperature. |
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