Magnetic shift register as counter and data storage device

A shift register comprising:

• a track comprising a ferromagnetic material and having a switchable magnetization orientation, the track having a first end and a second end;
• a first electrode at the first end and a second electrode at the second end to supply a first current to the track in a first direction and to supply a second current in a second direction, the second direction being opposite to the first direction;
• a first magnetic tunnel junction comprising a first ferromagnetic pinned layer, a first ferromagnetic free layer, and a first barrier layer therebetween, the track being the first free layer;
• and
• a second magnetic tunnel junction comprising a second ferromagnetic pinned layer, a second ferromagnetic free layer, and a second barrier layer therebetween, the track being the second free layer;
• wherein the first magnetic tunnel junction and the second magnetic tunnel junction stabilize a domain wall in the track.

A method comprising:

• providing a magnetic shift register having a ferromagnetic track and at least one domain wall anchor proximate the track, the track comprising a central portion intersecting an arm, the track having a magnetization orientation and the domain wall anchor having a magnetization;
• applying a magnetic field to the magnetic shift register at an angle of about 30-60 degrees to the track to:
• (a) pin the magnetization orientation of the domain wall anchor perpendicular to the magnetization orientation of the track;
• and
• (b) form a domain wall at the intersection of the track central portion and track arm.