A displacer assembly for a Stirling cycle system includes a displacer and a synchronous linear electric motor linked so as to drive the displacer. The electric motor features at least one stator assembly having first and second soft-magnetic pole pieces defining therebetween a gap. The width of the gap is oriented perpendicular to an axis of movement of the motor, and the stator assembly is constructed so as to generate a magnetic field aligned primarily parallel to the width of the gap. The motor also includes at least one compound permanent magnet system located within the gap. The compound permanent magnet system has a first section magnetized in a first direction parallel to the width of the gap and a second section axially displaced from the first section magnetized in a direction opposite to the first direction. The result of this structure is that the electric motor operates as a magnetic spring which, when no power is supplied to the motor, returns the displacer to a predefined rest position.