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RESEARCH |
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Thin Film Magnetic Materials | Thin Film Magnetic Devices | Magnetic Recording Systems Thin film magnetic materials have a host of technological applications, particularly in the data storage industry. My materials research focuses on soft magnetic materials, giant magnetoresistive materials, and magnetic recording media. Soft magnetic materials are those materials which magnetize easily in the direction of relatively small applied fields. They are just as useful at the microscopic size scale as they are at the macroscopic scale (where they have been used for decades in motors, generators, electromagnets, relays, etc.). In there microscopic application, they tend to be used as flux guides for the poles of magnetic recording heads, or to shield some structure, like a magnetoresistive head, from stray magnetic fields. Giant magnetoresistive materials are used as sensors
in magnetic recording heads. They are multilayered thin film structures
that display a resistance that changes with applied magnetic field.
With the above materials, it is possible to make a number of thin film devices, especially magnetic recording heads. The two questions that it is always necessary to ask about such devices are: "Can we build it?" and "Will it work?" The former is an issue of thin film processing design. Magnetic thin film devices are not so regimented in their fabrication processes as more traditional thin film fabrication process like a CMOS process, and it is frequently necessary to design a new set of fabrication steps for a new type of device. Ensuring that the device functions involves a combination of modeling and design and device testing. Before fabrication is done, sometimes it is necessary to do extensive analysis to properly design a device. For example, there is a possibility that a recording head will saturate before delivering enough field, or that it will not have sufficiently low inductance in order to permit high frequency operation. Proper device design can prevent these problems. After devices are fabricated, it is necessary to establish that the device actually does what it was designed to do. This may involve electrical probing in the presence of applied magnetic fields, recording tests, etc.
Ultimately, magnetic thin film devices must be shown to work within some larger system. Frequently, the system puts severe constraints on the operation of the device, or makes some very aggressive demand on the device performance. It is in this context that testing of the entire system performance becomes relevant. The question in this context is: "How is overall system performance being limited by the performance of this particular device?". This will often lead to insights on how to redesign the device to give better system performance. Improved device performance that does not lead to improved system performance is not a high leverage area for research. A important example of this is a magnetic recording system and its dependence on, among other things, head construction and performance. For this reason, we have developed a number of recording test beds within the DSSC to examine real heads and media.
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