Improved random-access memory cells, complementary cells, and memory devices. RRAM cells are provided for storing information in a plurality of programmable cell states. An electrically-insulating matrix is located between first and second electrodes such that an electrically-conductive path, which extends in a direction between the electrodes, can be formed within the matrix on application of a write voltage to the electrodes. The programmable cell states correspond to respective configurations of the conductive path in the matrix. An electrically-conductive component extends in a direction between the electrodes in contact with the insulating matrix. The arrangement is such that the resistance presented by the component to a cell current produced by a read voltage applied to the electrodes to read the programmed cell state is at least about that of the conductive path and at most about that of the insulating matrix in any of the cell states.