Using Raman Spectroscopy*

Strong anisotropic behavior of Raman modes has been detected in polarized Raman spectroscopy of a ternary compound NbIrTe₄ nanoflake. 19 Raman modes of A₁ and A₂ symmetries were detected and were consistent with DFT calculations. By rotating the sample the Raman spectroscopy probes different directions of the crystal structure. These measurements were implemented so that the polarization direction of the incident and scattered beams are parallel and perpendicular, respectively. Through analysis of this angular dependence one can extract the Raman tensor elements which depend on electron-phonon coupling. By exciting at 633 nm and 514 nm, it is possible to observe the sensitivity of the tensor elements to excitation energy for 19 Raman modes. We find that the mode excitation sensitivity depend strongly on their frequency which indicates that some modes couple much more strongly to electronic states than others.