  The extraordinary properties of two dimensional (2D) materials, such as the
extremely high carrier mobility in graphene and the large direct band gaps in
transition metal dichalcogenides MX2 (M = Mo or W, X = S, Se) monolayers,
highlight the crucial role quantum confinement can have in producing a wide
spectrum of technologically important electronic properties. Currently one of
the highest priorities in the field is to search for new 2D crystalline systems
with structural and electronic properties that can be exploited for device
development. In this letter, we report on the unusual quantum transport
properties of the 2D ternary transition metal chalcogenide - Nb3SiTe6. We show
that the micaceous nature of Nb3SiTe6 allows it to be thinned down to
one-unit-cell thick 2D crystals using microexfoliation technique. When the
thickness of Nb3SiTe6 crystal is reduced below a few unit-cells thickness, we
observed an unexpected, enhanced weak-antilocalization signature in
magnetotransport. This finding provides solid evidence for the long-predicted
suppression of electron-phonon interaction caused by the crossover of phonon
spectrum from 3D to 2D.
