Abstract:
A magnetic sensor assembly includes first and second shields each comprised of a magnetic material. The first and second shields define a physical shield-to-shield spacing. A sensor stack is disposed between the first and second shields and includes a seed layer adjacent the first shield, a cap :layer adjacent the second shield, and a magnetic sensor between the seed layer and the cap layer. At least a portion of the seed layer and/or the cap layer comprises a magnetic material to provide an effective shield-to-shield spacing of the magnetic sensor assembly that is less than the physical shield-to-shield spacing.
Abstract:
A spin-transfer torque memory apparatus and self-reference read schemes are described. One method of self-reference reading a spin-transfer torque memory unit includes applying a first read current through a magnetic tunnel junction data cell and forming a first bit line read voltage. Then applying a low resistance state polarized write current through the magnetic tunnel junction data cell, forming a low second resistance state magnetic tunnel junction data cell. A second read current is applied through the low second resistance state magnetic tunnel junction data cell to forming a second bit line read voltage. The method also includes comparing the first bit line read voltage with the second bit line read voltage to determine whether the first resistance state of the magnetic tunnel junction data cell was a high resistance state or low resistance state.
Abstract:
A method and apparatus for stray magnetic field compensation in a non-volatile memory cell, such as a spin-torque transfer random access memory (STRAM). In some embodiments, a first tunneling barrier is coupled to a reference structure that has a perpendicular anisotropy and a first magnetization direction. A recording structure that has a perpendicular anisotropy is coupled to the first tunneling barrier and a nonmagnetic spacer layer. A compensation layer that has a perpendicular anisotropy and a second magnetization direction in substantial opposition to the first magnetization direction is coupled to the nonmagnetic spacer layer. Further, the memory cell is programmable to a selected resistance state with application of a current to the recording structure.