The Evident of Coupled Spin and Electron-phonon Interactions in Cd2Os2O7 Pyrochlore

Abstract

We present the results of the temperature dependence of the Raman spectra of pyrochlore Cd2Os2O7 single crystal in a temperature range of 100-270 K. We found that, among the six observed Raman active modes, the 762 cm-1 phonon has a significant peak shift and asymmetric Fano lineshape. The temperature-dependent of the frequency and full width at half maximum (FWHM) of the phonon shows the kinks near the Néel temperature. The complex temperature-dependent asymmetry Fano parameter and the anomalies of the FWHM below Néel temperature indicate coupling of the 762 cm-1 phonon to both electron and spin degrees of freedom. In addition, we found the Fano asymmetry rapidly drops below the Néel temperature towards its minimum value of ~ 200 K. Thus, at temperature ranging from 200 K to TN, the pyrochlore is suggested to be in an all-in -all-out ordered semimetallic state. We also confirm that Raman scattering temperature dependence provides a simple and powerful method for investigating temperature transitions and coupling in pyrochlore materials.