Microwave collective transport in single-crystalEu2CuO4

We measured the complex conductivity of single crystals of ${\mathrm{Eu}}_2$ ${\mathrm{CuO}}_4$ from 3 to 15 GHz and observed collective transport with a sample-independent spectral weight. An unusual activated temperature dependence for the spectral weight, and anomalous temperature dependence of the Eu Mossbauer line, indicate magnetic effects well above the Néel temperature. The collective transport is similar to that observed in (TMTSF${)}_2$ ${\mathrm{PF}}_6$ where TMSF denotes tetramethyltetrathiofulvalene and where charged, massive solitons are the suspected source of the transport.