Bipolar spin-transfer switching

A magnetic device comprising:

• a magnetized polarizing layer;
• a free magnetic layer, the free magnetic layer forming a first electrode and separated from the magnetized polarizing layer by a first non-magnetic metal layer, the free magnetic layer having a magnetization vector having a first stable state and a second stable state;
• a reference layer forming a second electrode and separated from the free-magnetic layer by a second non-magnetic layer, the reference layer having a fixed magnetization vector;
• a current source that sources unipolar current through the magnetized polarizing layer, the free magnetic layer and the reference layer, the current source is capable of outputting a first unipolar current pulse of a first duration and having a selected amplitude, the first unipolar current pulse flowing orthogonally through the polarizing layer and having a positive polarity, the current source also capable of outputting a second unipolar current pulse of a second duration and having a selected amplitude, the second unipolar current pulse flowing orthogonally through the polarizing layer and having a negative polarity, and
• wherein switching of the magnetization vector of the free magnetic layer from the first stable state to the second state is initiated by application of the first unipolar current pulse, and wherein switching of the magnetization vector of the free magnetic layer from the second stable state to the first stable state is initiated by application of the second unipolar current pulse, wherein switching to the second stable state is independent of the first duration of the first unipolar current pulse, and wherein switching to the first stable state is independent of the second duration of the second unipolar current pulse.