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Polarized Raman spectra of the ferromagnetic metal CrO 2 were measured in a broad temperature range including T c Ϸ390 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 isostructural TiO 2 . 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, the 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. ͓S0163-1829͑99͒00825-5͔

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