Dynamics of the charge-spin interplay in a perovskite manganite

The interplay between charge and spin degrees of freedom is a key ingredient of the colossal magnetoresistance in perovskite manganites. However, our knowledge of such an interplay was limited to its static aspect, and very little was known regarding its dynamics. Here, we show that the ac (optical) conductivity of perovskite manganite Pr_0.6Sr_0.4MnO₃ (T_C=297 K) under magnetic field does not show such a universal M² scaling (M is the magnetization) as observed in the dc conductivity, but shows a marginal ∣M∣¹ dependence in the critical regime. This result indicates a unique interplay between fluctuating spin and charge in this series of compounds.