A phase change memory device having an increased sensing margin for improved cell efficiency. The system comprises a control system including a microprocessor arranged to control a pulse amplitude modulated voltage controlled current circuit, and may employ a monitor for monitoring at least one ambient condition and a microprocessor operable to control the current circuit in response to the monitored condition. The shift enable provides for synchronization to facilitate the cell-by-cell write and reset. The elastic membrane of the abutment member comprises an abutment portion, having a flange projecting outwardly, brought into direct or indirect contact with the substrate, and a connecting portion extending upwardly from a base portion of the flange of the abutment portion and being connected to the vertically movable member.