Raman spectroscopy of ferromagnetic CrO2

Polarized Raman spectra of the ferromagnetic metal CrO2 were measured in a broad temperature range including T(c)approximate to 390 K. The Raman-allowed modes of A(1g) , B-1g , B-2g , and E-g symmetry were identified and compared to the corresponding modes of isostructnral TiO2. The two low-frequency Raman lines are relatively narrow, indicating weak scattering of the corresponding B-1g and E-g phonons. Whereas the Raman intensities are not visibly affected by the magnetic ordering, tlbe dependences on temperature of the phonon wave numbers exhibit peculiarities that could be attributed to a spin-phonon interaction. The variations with T of the phonon linewidths follow at low temperatures the dependence expected for phonon-phonon scattering. An additional broadening at higher temperatures with a maximum near T-c is tentatively assigned to scattering from collective spin fluctuations. [S0163-1829(99)00825-5].