Atomic force microscope system with cantilever having unbiased spin valve magnetoresistive strain gauge

An atomic force microscope system for scanning the surface of a sample, the system comprising:

• a sample holder;
• a cantilever having a fixed end, a free end, and a length terminating at the free end as a cantilever tip;
• a spin valve magnetoresistive structure comprising a plurality of films formed on the cantilever;
• electrical resistance detection circuitry coupled to the spin valve structure on the cantilever for detecting changes in electrical resistance of the spin valve structure in response to deflection of the cantilever tip;
• and
• an actuator for moving the cantilever tip and the sample holder relative to one another, whereby the sample held in the sample holder causes deflection of the cantilever tip during scanning and the deflection is detected by the electrical resistance detection circuitry.

An atomic force microscope-based data storage disk drive comprising:

• a data storage disk having on its surface a plurality of data tracks of surface incongruences representing machine-readable information;
• a motor for rotating the disk;
• a flexible cantilever having a fixed end, a free end, and a contact stylus on its free end for engaging and contacting the surface incongruences on the disk during rotation of the disk;
• a spin valve magnetoresistive strain gauge formed on the cantilever and comprising a free ferromagnetic layer having nonzero magnetostriction and whose magnetic moment is free to rotate in the presence of an applied magnetic field, a pinned ferromagnetic layer, an antiferromagnetic layer formed on and in contact with the pinned ferromagnetic layer for pinning the magnetic moment of the pinned layer, and a nonferromagnetic metallic conducting spacer layer located between and in contact with the free and pinned ferromagnetic layers;
• electrical resistance detection circuitry coupled to the spin valve magnetoresistive strain gauge;
• whereby, in the absence of an applied magnetic field, applied stresses to the free ferromagnetic layer due to deflection of the cantilever when the stylus contacts surface incongruences on the disk give rise to angular displacements of the magnetic moment of the free layer and a resulting change in the electrical resistance of the spin valve magnetoresistive strain gauge;
• an actuator connected to the cantilever for maintaining the stylus on a data track;
• and
• a data decoding circuit for receiving the output signal from the electrical resistance detector and for converting the output signal to digital data signals representative of the machine-readable information formed by the surface incongruences on the disk.