We present inelastic light scattering measurements of EuO and (formula presented) (formula presented) 0.005, 0.01, 0.03, and 0.05) as functions of doping, B isotope, magnetic field, and temperature. Our results reveal a variety of distinct regimes as a function of decreasing T: (a) a paramagnetic semimetal regime, which is characterized by a collision-dominated electronic scattering response whose scattering rate (formula presented) decreases with decreasing temperature; (b) a spin-disorder scattering regime, which is characterized by a collision-dominated electronic scattering response whose scattering rate (formula presented) scales with the magnetic susceptibility; (c) a magnetic polaron regime, in which the development of an (formula presented) spin-flip Raman response betrays the formation of magnetic polarons in a narrow temperature range above the Curie temperature (formula presented) and (d) a ferromagnetic metal regime, characterized by a flat electronic continuum response typical of other strongly correlated metals. By exploring the behavior of the Raman responses in these various regimes in response to changing external parameters, we are able to investigate the evolution of charge and spin degrees of freedom through various transitions in these materials. © 2001 The American Physical Society.
Publication Source (Journal or Book title)
Physical Review B - Condensed Matter and Materials Physics
Snow, C., Cooper, S., Young, D., Fisk, Z., Comment, A., & Ansermet, J. (2001). Magnetic polarons and the metal-semiconductor transitions in (formula presented) and EuO: Raman scattering studies. Physical Review B - Condensed Matter and Materials Physics, 64 (17) https://doi.org/10.1103/PhysRevB.64.174412