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High Resolution Phonon-assisted Quasi-resonance Fluorescence Spectroscopy
Published on: June 28, 2016
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Phonon Anharmonicity in Bulk T d -MoTe2.
Jaydeep Joshi1, Iris Stone1, Ryan Beams2
1Department of Physics and Astronomy, George Mason University, Fairfax, VA 22030, USA.
Applied Physics Letters
|November 2, 2020
Summary
Anharmonic effects in bulk Td-molybdenum ditelluride (MoTe2) were studied using Raman spectroscopy. Below 100 K, nonlinear frequency shifts indicate optical phonon decay, suggesting phonon-phonon interactions dominate at low temperatures.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Spectroscopy
Background:
- Bulk Td-molybdenum ditelluride (MoTe2) is a material with interesting electronic properties.
- Understanding phonon behavior is crucial for predicting material properties.
- Anharmonicity in phonon modes influences thermal and electronic transport.
Purpose of the Study:
- To investigate anharmonic contributions to optical phonon modes in bulk Td-MoTe2.
- To explore temperature-dependent changes in phonon frequencies, intensities, and linewidths.
- To correlate observed phenomena with the structural phase transition.
Main Methods:
- Temperature-dependent Raman spectroscopy was employed.
- Measurements were conducted across a temperature range from 100 K to 200 K, with observations below 100 K.
- Analysis involved comparing experimental data with the Grüneisen model.
Main Results:
- Linear temperature-dependent redshift of phonon modes was observed between 100 K and 200 K, consistent with the Grüneisen model.
- Nonlinear temperature-dependent frequency shifts were detected below 100 K, attributed to optical phonon decay into acoustic phonons.
- Significant changes in intensity and linewidth of high-frequency Raman modes near 250 K correlated with the Td to 1T' structural phase transition.
Conclusions:
- Phonon-phonon interactions are identified as dominant anharmonic contributions at low temperatures in bulk Td-MoTe2.
- The study provides insights into the anharmonic behavior of MoTe2, relevant for understanding Weyl semimetals.
- Observed anharmonicity is linked to fundamental interactions influencing material properties.
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