A magnetic double tunnel junction (MDTJ) (which, preferably, has a large aspect ratio, wherein length L of the MDTJ>>width w of the MDTJ) has magnetic domain wall(s) or DW(s) in the free layer of the MDTJ, wherein controlled movement of the DW(s) across the free layer is effected in response to the polarity, magnitude, and duration of a voltage pulse across the MDTJ. The motion and relative position of DW(s) causes the conductance of the MDTJ (that is measured across the MDTJ) to change in a symmetric and linear fashion. By reversing the polarity of the bias voltage, the creation and/or direction of the DW(s) motion can be reversed, thereby allowing for a bi-directional response to the input pulse.