Seminarium Fizyki Jądra Atomowego
sala 1.01, ul. Pasteura 5
2026-10-15 (10:15) 
prof. dr hab. Adam Babiński (ZFCS IFD, Wydział Fizyki UW)
The effect of Ge isotopes on the Raman scattering in CrGeTe3
The effects of isotopes on properties of bulk semiconductors were intensively studied twenty years ago. Germanium and silicon, the first semiconductors of technological importance, were the focus of thoseinvestigations. In particular, their lattice dynamics were clearly affected by the varying mass of the involved atoms.
We address this effect in chromium germanium telluride (CrGeTe3), a van der Waals (vdW) semiconducting ferromagnet. CrGeTe3 is characterized by strong magneto-elastic coupling, which justifies studies of its latticedynamics, with Raman scattering spectroscopy as a tool of choice.
We investigated Raman scattering in CrGeTe3. We revealed a fine structure of the highest-energy Raman active mode corresponding to the vibrations of the Ge-Ge pseudomolecule in the material. Its lineshapeconsists of eleven closely spaced spectral features [1]. We explain the lineshape in terms of naturally occurringdistribution of Ge isotopes in the material.
We also investigated Raman scattering in CrGeTe3 isotopically enriched with 70Ge. The fine structure of the mode disappears in the enriched sample, the and only one line of the multiplet could be observed at the energy, assigned to the 70Ge -70Ge pseudomolecule configuration in the natural crystal. The experimental finding isconsistent with density functional theory calculations, which supports our attribution.
Our findings draw renewed attention to isotopically-enriched vdW materials. The CrGeTe3 crystal structureis shared by numerous materials with diverse properties. While the fine structure of the Raman-active modecorresponding to Si pseudo-molecule vibrations-reflecting the isotope composition of natural silicon - has already been observed, many related materials, remain to be investigated to reveal the possible effects of Ge/Si isotopes on their fundamental properties.
[1] G. Krasucki G. et al., arXiv:2510.01881
We address this effect in chromium germanium telluride (CrGeTe3), a van der Waals (vdW) semiconducting ferromagnet. CrGeTe3 is characterized by strong magneto-elastic coupling, which justifies studies of its latticedynamics, with Raman scattering spectroscopy as a tool of choice.
We investigated Raman scattering in CrGeTe3. We revealed a fine structure of the highest-energy Raman active mode corresponding to the vibrations of the Ge-Ge pseudomolecule in the material. Its lineshapeconsists of eleven closely spaced spectral features [1]. We explain the lineshape in terms of naturally occurringdistribution of Ge isotopes in the material.
We also investigated Raman scattering in CrGeTe3 isotopically enriched with 70Ge. The fine structure of the mode disappears in the enriched sample, the and only one line of the multiplet could be observed at the energy, assigned to the 70Ge -70Ge pseudomolecule configuration in the natural crystal. The experimental finding isconsistent with density functional theory calculations, which supports our attribution.
Our findings draw renewed attention to isotopically-enriched vdW materials. The CrGeTe3 crystal structureis shared by numerous materials with diverse properties. While the fine structure of the Raman-active modecorresponding to Si pseudo-molecule vibrations-reflecting the isotope composition of natural silicon - has already been observed, many related materials, remain to be investigated to reveal the possible effects of Ge/Si isotopes on their fundamental properties.
[1] G. Krasucki G. et al., arXiv:2510.01881