A combined experimental and theoretical study of the structural, electronic and vibrational properties of bulk and few-layer Td-WTe2. (23rd June 2015)

• Record Type: Journal Article
• Authors: Jana, Manoj K; Singh, Anjali; Late, Dattatray J; Rajamathi, Catherine R; Biswas, Kanishka; Felser, Claudia; Waghmare, Umesh V; Rao, C N R
• Is Part Of: Journal of physics. Volume 27:Number 28(2015)
• Publication Date: 2015-06-23
• Subjects: tungsten ditelluride -- Td-structure -- Raman spectroscopy; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/0953-8984/27/28/285401
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: The recent discovery of non-saturating giant positive magnetoresistance has aroused much interest in Td-WTe2 . We have investigated structural, electronic and vibrational properties of bulk and few-layer Td-WTe2 experimentally and theoretically. Spin–orbit coupling is found to govern the semi-metallic character of Td-WTe2 and its structural link with the metallic 1 T form provides an understanding of its structural stability. There is a metal-to-insulator switch-over in the electrical conductivity and a change in the sign of the Seebeck coefficient around 373 K. Lattice vibrations of Td-WTe2 have been analyzed using first-principles calculations. Out of the 33 possible zone-center Raman active modes, five distinct Raman bands are observed around 112, 118, 134, 165 and 212 cm −1 in bulk Td-WTe2 . Based on symmetry analysis and calculated Raman tensors, we assign the intense bands at 165 cm −1 and 212 cm −1 to the and modes, respectively. Most of the Raman bands stiffen with decreasing thickness, and the ratio of the integrated intensities of the to bands decreases in the few-layer sample, while all the bands soften in both the bulk and few-layer samples with increasing temperature.