Generation and detection of coherent longitudinal acoustic waves in ultrathin 1T'-MoTe2

Abstract

Layered transition metal dichalcogenides have attracted substantial attention owing to their versatile functionalities and compatibility with current nanofabrication technologies. Thus, noninvasive means to determine the mechanical properties of nanometer (nm) thick specimens are of increasing importance. Here, we report on the detection of coherent longitudinal acoustic phonon modes generated by impulsive femtosecond (fs) optical excitation. Broadband fs-transient absorption experiments in 1T'-MoTe2 flakes as a function of thickness (7 nm - 30 nm) yield a longitudinal sound speed of 2990 m/s. In addition, temperature dependent measurements unveil a linear decrease of the normalized Young's modulus with a slope of -0.002 per K and no noticeable change caused by the Td - 1T' structural phase transition or variations in film thickness.

The following article has been accepted by Applied Physics Letters

References in corpus (3)

• Activation of new Raman modes by inversion symmetry breaking in type II Weyl semimetal candidate T'-MoTe2
• Dimensionality-driven orthorhombic MoTe2 at room temperature
• Sound velocity and absorption measurements under high pressure using picosecond ultrasonics in diamond anvil cell. Application to the stability study of AlPdMn

Cited by in corpus (2)

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