A multiphase selector includes a first electrode, a switching layer coupled to the first electrode, a capping layer coupled to the switching layer, and a second electrode coupled to the capping layer. The switching layer may include a matrix having a first, relatively insulating phase of a transition metal oxide; a second, relatively conducting phase of the transition metal oxide dispersed in the matrix; and a catalyst, located within the matrix, to interact with the first phase of the transition metal oxide to selectively form and position the second phase of the transition metal oxide within the matrix.