Abstract: A specially designed, forceful, compact magnetic micro-mover includes at least one etched single crystal silicon plate having integral springs and stable, low internal stress. A structure of springs which support a rectangular plate are etched in silicon. The plate is driven by planar electromagnetic actuation. The micro-mover consists of a specific etched silicon spring in combination with a planar electromagnetic moving coil actuator that is capable of generating forces greater than 50 mN, while dissipating less than 1 W peak power. The micro-mover also includes a plate suspension system that facilitates the required plate motions and resolution, while preventing changes in plate spacing from effects such as external acceleration, temperature, humidity, and aging; and includes an actuator that appropriately moves the plates in response to electrical signals, such that there is only minimal cross-talk between axes of motion.

Abstract: Providing a magnetic head with a yoke and a gap structure coupled to a substrate that is positioned above a magnetic medium. The gap structure includes one or more lips, a first and a second ferromagnetic pole, and a magnetoresistive element (MRE). The magnetoresistive element is removed from the air-bearing surface of the magnetic head. For the embodiment with two lips, the two lips define a head gap. Each ferromagnetic pole is connected to one lip. The two poles are separated by a distance greater than the length of the gap, and each pole has a thickness that is greater than the thickness of each lip. The MRE is substantially coupled magnetically, but not electrically to the two poles at a location where the two poles are separated by a distance greater than the length of the gap.

Abstract: A planar silicon magnetoresistive read/write head has separate read and write gaps that can be individually optimized. The write gap includes a write gap shunt that suppresses signals that are read across the write gap without interfering with the ability of the head to generate write signals at the write gap. The head retains both the advantages of removing the magnetoresistive element from the air bearing surface to avoid wear, shorting, and corrosion, and to eliminate cross-track asymmetry, associated with dual gap magnetoresistive heads; and the advantages of low cost fabrication and high area density, associated with silicon planar head structures.

Abstract: In a magnetoresistive transducer, a conductor configuration in which magnetic fields in the conductors are oriented in the same direction to provide symmetric track profiles and improved track edge response. Conductor area at the transducer air bearing surface is also minimized to eliminate shorting and improve device yield and reliability. In one embodiment of the invention, inductive pickup is minimized by limiting the active width of magnetoresistive sensing elements through conductor placement. Another embodiment of the invention, useful for applications involving dual stripe magnetoresistive transducers, minimizes inductive pickup by providing relatively large conductors for each magnetoresistive stripe, arranged in parallel with each other and coupled differentially to cancel inductive pickup through common mode rejection.

Abstract: A magnetoresistive transducer includes at least one magnetoresistive element having a transverse easy axis. The use of a transverse easy axis prevents magnetic domains from forming in the magnetoresistive elements and results in a noise-free device. Various techniques for producing a transverse easy axis include the use of stress, and a magneto strictive material, during the formation of the element to orient the anisotropy of the element transverse to orient the anisotropy of the element transverse to the element, formation of the element in the presence of a magnetic field, high temperature anneal of the element, or any other method of forming the element with a prebiased state.

Abstract: A head structure for reading and writing perpendicular transitions from and to a moving recording medium. The head structure comprises an auxiliary magnetic pole having a tapered edge adjacent its air bearing surface that is oriented transverse to the direction of motion of a recording medium. A magnetoresistive gradiometer employed as the read mechanism is formed within a layer of insulating material disposed on the auxiliary pole member. The gradiometer comprises two magnetoresistive members separated by dielectric material, and two shield members disposed on opposite sides of the magnetoresistive members. The shield members shield the magnetoresistive members from undesired magnetic fields and thus improve the resolution of the signals read from the medium. A coil is formed on and encapsulated within a layer of photoresist material deposited above the layer of insulating material.

Abstract: A magnetoresistive head structure that incorporates a thin film magnetoresistive transducer that is suitable for use in perpendicular and longitudinal recording heads. This structure includes first and second dielectrically separated magnetoresistive members that have noncontacting first ends. Sense conductors are disposed in contact with the first ends of the magnetoresistive members and are adapted to provide sense currents thereto. A bias current conductor arrangement is disposed adjacent to the magnetoresistive members and is separated therefrom by dielectric and is adapted to provide bias current thereto. A common conductor is disposed in contact with the second ends of the magnetoresistive members and is adapted to short the second ends thereof and provide a return path for the sense and bias currents. In one embodiment, the bias conductor arrangement passes between the magnetoresistive members and thus provides for longitudinal transition detection.

Abstract: A sensor for reading perpendicularly recorded media includes dual magneto-resistive elements. Directionally opposed currents through respective elements each serve both sensing and bias functions. A detector differentially detects changes in the resistance of the stripes so as to presume common mode noise rejection when reading perpendicular recording media. In addition, the opposing currents offset each other's interaction with the soft magnetic underlayer of the media, which interaction could otherwise perturb the information stored on the media. Provision is made for switching the relative direction of current flow to provide for reading longitudinally recorded media.

Abstract: The manufacture of digital magnetic recording discs for computer disc drives requires the monitoring and control of the M-H hysteresis loop properties of the magnetic film deposited on the disc substrate. Several methods exist for measuring this M-H hysteresis loop, but they all have serious disadvantages. One method consists of cutting samples and measuring them with a vibrating sample magnetometer. This is a destructive test and requires a lot of time per sample. Another method uses the Kerr-rotation of polarized light. However, it samples only the mangetization of the surface and cannot determine the magnetic thickness of the film. A third method magnetizes the entire disc and samples a large region along a diameter. This method cannot distinguish between the top and bottom films of the disc, and cannot resolve circumferential variations of th M-H loop properties.

Abstract: A gradiometer for measuring magnetic field gradients. The gradiometer is formed by a number of magnetic field sensing devices. Each device has its own axis of sensitivity and produces a signal proportional to the magnetic field strength in the direction of its axis of sensitivity. The devices are mounted so that the different axes of sensitivity are at different angles to each other and so that at least some of the devices are displaced from each other along a common axis. The signals from the devices are combined so as to balance out unwanted components, particularly those due to the earth's magnetic field.

Abstract: A superconducting magnetic sensor having a sensing coil is provided with one or more superconducting discs for adjusting the effective area of the coil. The effective area of the coil is adjusted by varying the position of the superconducting disc relative to the associated coil. In a superconducting gradiometer having a pair of sensing coils coupled in series opposition, three superconducting discs are arranged to provide effective area adjustment along three mutually orthogonal axes. Coarse and fine adjustment are optionally provided by employing two sets of superconducting discs, one set fixed, the other adjustable.

Abstract: One or more primary superconductive magnetic field pickup coils are trimmed by means of one or more auxiliary super-conductive trim coils coupled to a magnetic flux sensor for sensing the magnetic flux coupled to the sensor by said primary and auxiliary coil circuits. The trim coils preferably each have their respective magnetic axes oriented orthogonally to each other for independent adjustment. The trim coils are wound in the gradient configuration and an adjustable superconductive magnetic shield is provided surrounding each of the respective trim coils for varying the coupling between the respective trim coil and the magnetic field by varying the position of the magnetic shield relative to a null or symmetric position relative to the trim coil. In a preferred embodiment, there are three mutually orthogonal trim coils.