Coupled spin-charge-phonon fluctuation in the all-in/all-out antiferromagnet Cd2Os2O7

A. Koda, H. T. Hirose, M. Miyazaki, H. Okabe, M. Hiraishi, I. Yamauchi, K. M. Kojima, I. Nagashima, J. Yamaura, Z. Hiroi, R. Kadono
2019 Physical review B  
We report on a novel spin-charge fluctuation in the all-in-all-out pyrochlore magnet Cd$_2$Os$_2$O$_7$, where the spin fluctuation is driven by the conduction of thermally excited electrons/holes and associated fluctuation of Os valence. The fluctuation exhibits an activation energy significantly greater than the spin-charge excitation gap and a peculiar frequency range of $10^{6}$--$10^{10}$ s$^{-1}$. These features are attributed to the hopping motion of carriers as small polarons in the
more » ... olarons in the insulating phase, where the polaron state is presumably induced by the magnetoelastic coupling via the strong spin-orbit interaction. Such a coupled spin-charge-phonon fluctuation manifests as a part of the metal-insulator transition that is extended over a wide temperature range due to the modest electron correlation comparable with other interactions characteristic for 5$d$-subshell systems.
doi:10.1103/physrevb.100.245113 fatcat:6k3hwcu5rrc6zepqhfolfn5ymm