Spin-phonon coupling in rod-shaped half-metallic CrO2 ultrafine particles: A magnetic Raman scattering study

Abstract

Half-metallic CrO2 powder compact with rod-shaped nanoparticles was studied by micro-Raman scattering in the presence of an external magnetic field at room temperature (300 K). In the low-field region (H ≤ 250 mT), the frequency and intensity of the Eg mode, an internal phonon mode of CrO2, increase dramatically with increase in the magnetic field, while the corresponding linewidth decreases. The above parameters become constant when the CrO2 powder enters the saturation state at higher magnetic field. The pronounced anomalies of the Raman phonon parameters under a low magnetic field are attributed to the spin-phonon coupling enhanced by the magnetic ordering, which is induced by the external magnetic field.