2D correlation analysis (2DCOS) and principal component analysis (PCA) have been performed on temperature-dependent Raman spectra from 12 K to 300 K of SmB 6 single crystals grown from Boron with a purity of 99.9% (3N) or 99.9999% (6N). Significant differences in the Raman spectra of SmB 6 (3N) and SmB 6 (6N) are observed. The Raman active T 2g , E g , and A 1g modes of SmB 6 (3N) are broader and shift to higher wavenumbers compared with those of SmB 6 (6N). The results of 2DCOS and PCA on temperature-dependent Raman spectra of SmB 6 (3N) and SmB 6 (6N) give us further information. We find that all the T 2g , E g , and A 1g modes of SmB 6 (6N) are single bands, while those of SmB 6 (3N) show all doublet features. The appearance of multiple bands in Raman vibrational modes of SmB 6 (3N) sample implies that the structure of boron octahedra of the SmB 6 (3N) has lower symmetry than that of SmB 6 (6N). Our findings in 2DCOS and PCA of the Raman spectra strongly support the differences in the behavior of SmB 6 (3N) and SmB 6 (6N).
- 2D correlation spectroscopy (2DCOS)
- Overlapped peaks
- Principal component analysis (PCA)
- Raman spectroscopy