Kohn anomaly in the 1T2phase of TaS2
- 1 July 1977
- journal article
- Published by IOP Publishing in Journal of Physics F: Metal Physics
- Vol. 7 (7) , 1139-1143
- https://doi.org/10.1088/0305-4608/7/7/015
Abstract
Neutron scattering studies on the 1T2 phase of TaS2 at room temperature reveal a strong Kohn anomaly in the longitudinal phonon mode propagating in the (100) direction. The anomaly occurs at a wavevector 0.27a* comparable to the radius of circles of diffuse intensity seen in electron diffraction patterns. The elastic nature of satellites arising from the noncommensurate lattice distortion has been established. Although the system is essentially two-dimensional the in-plane longitudinal sound velocity is not significantly larger than that perpendicular to the layer. From the (001) zone boundary acoustic modes the authors have determined the frequency of the 'rigid layer' modes to be nu shear=0.78 THz (26 cm-1) and nu comp=1.51 THz (50.3 cm-1).Keywords
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