Testing current perpendicular to plane giant magnetoresistance multilayer devices

A device comprising:

• a substrate;
• a conductive base layer on the substrate;
• and
• a magnetic multilayer comprising a magnetic material on the conductive base layer,
• wherein the magnetic multilayer comprises at least one ring-shaped, first continuous portion of the magnetic multilayer which surrounds a hole in the magnetic multilayer, and a second portion of the magnetic multilayer separated from said first continuous portion by a trench surrounding the first continuous portion of the magnetic multilayer wherein the diameter of the trench, hole and testing ring, taken together, is less than 10 micrometer.

A method for determining a property of current perpendicular to the plane of a device including a substrate, a conductive base layer on the substrate and a magnetic multilayer containing a magnetic material on the conductive base layer comprising the steps of:

• forming at least one hole in the magnetic multilayer of the device and a trench around the at least one hole to isolate at least one first continuous portion of the magnetic multilayer around the at least one hole from a second portion of the magnetic multilayer wherein the diameter of the trench, hole and testing ring, taken together, is less than 10 micrometer;
• and
• determining the property of the device by electrically contacting a probe with the at least one first continuous portion of the magnetic multilayer, applying a predetermined voltage to the probe;
• and measuring a voltage or a current at the conductive base layer.