Wydarzenia

Seminarium Fizyki Politechniki Wrocławskiej

Raman scattering spectroscopy of layered Cr₂Ge₂Te₆ ferromagnet -
Spin-phonon coupling and isotope-related Ge-Ge pseudo-molecule vibrations

Prof. Adam Babiński

Faculty of Physics, University of Warsaw

Raman scattering (RS) spectroscopy of chromium germanium telluride (Cr2Ge2Te6, CGT) is reported. Ten Raman-active modes: 5Ag and 5Eg, predicted by the density functional theory are identified using polarization-resolved RS measurements. The effect of temperature on the RS spectra of CGT from T=5 K to T=300 K is also investigated. A strong magneto-phonon coupling in CGT is revealed at temperatures of about 150 K and 60 K, which is associated with the emergence of the local magnetic order and the transition to the complete ferromagnetic phase, respectively. Moreover, a unique fine structure of the highest-energy Raman A5g peak is revealed. Up to 11 related Raman features can be observed. We show that the structure can be very well simulated using a model of Ge-Ge pseudo-molecules for various Ge isotopes. It has been found that the intensity of the corresponding peaks reflects the abundance of Ge in natural material and their energies result from masses of isotopes in question.