We report an electronic Raman scattering study of the colossal magnetoresistance (CMR) manganese perovskites as a function of temperature, magnetic field, symmetry, and doping. The low-frequency electronic Raman spectrum in the paramagnetic-insulating phase of these materials is characterized by a diffusive Raman-scattering response, while a nearly flat continuum response is observed in the ferromagnetic-metallic state. We found that the (Formula presented)-symmetry electronic scattering intensity is significantly reduced with applied magnetic field near (Formula presented) in a manner reminiscent of the dc magnetoresistivity. The strongly field-dependent scattering rate in the (Formula presented) channel appears to reflect the highly field-dependent mobility along the Mn-O bond direction expected in the double exchange mechanism. In addition, we observe a persistent field dependence in the (Formula presented) electronic scattering response for (Formula presented) suggesting that the ferromagnetic phase is inhomogeneous, perhaps consisting of both metallic and insulating components.
|頁（從 - 到）||R10115-R10118|
|期刊||Physical Review B - Condensed Matter and Materials Physics|
|出版狀態||已發佈 - 1998|
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