Conducting phase of rapidly cooledAC60(A=Cs and Rb)

A three-dimensional (3D) conducting phase is found upon rapid cooling below 150 K for ${\mathrm{CsC}}_{60}$ and below 125 K for ${\mathrm{RbC}}_{60}$. Electron-spin resonance, differential thermal analysis, differential scanning calorimetry, and x-ray-diffraction results suggest that the 3D conducting phase is an orientationally ordered (possibly simple-cubic) phase. We propose a complete relation for the various states for A${\mathrm{C}}_{60}$. The rapidly cooled A${\mathrm{C}}_{60}$ shows a number of phase changes as the temperature increases from 4 to 473 K.