Orientational ordering of C-60 in the antiferromagnetic (NH3)K3C60 phase -art. no. 132414

The absence of superconductivity in the ammoniated alkali fulleride, (NH3)K 3C60, and the transition to an antiferromagnetic (AF) Mott insulating groun d state have been associated with the combined effects of crystal symmetry lowering and increased interfullerene separation. We find that the low-temp erature orientational ordering motif of the C-60 units in the perdeuterated analog, (ND3)K3C60, correlates well with the three-dimensional AF structur e proposed by NMR, which arises through alternate stacking of two-dimension al sheets of C-60, which order ferrorotationally (antiferromagnetically) al ong the [110] and antiferrorotationally (ferromagnetically) along the [1 (1 ) over bar0] directions.