Dr. Song Xue
CEO, MultiDimension Technology
October 3, 2014 | 10:00 to 11:00 | Swarm Lab Immersion Room, 490 Cory Hall
Host: John Huggins
Magnetic transducers are widely used in modern industry and electronics to sense magnetic field strength to measure current, position, motion, direction and other physical parameters. Commercially important approaches, in order of technical advancement, include Hall Effect, Anisotropic MagnetoResistance (AMR), Giant MagnetoResistance (GMR), and the latest, Tunneling MagnetoResistance (TMR), which has quickly become the dominant technology for the most demanding of magnetic sensing applications: high-density hard disk drives. Hall elements have large power consumption and poor non-linearity. The AMR element has much higher sensitivity than the Hall element, but it has a narrow linear operating range. The AMR magnetic sensor elements need to use a set/reset coil for their preset/reset operation which results in increased complexity of their manufacturing process while also increasing their size and power consumption. GMR magnetic sensing element sensitivity is higher than AMR, but its linear range is still low. Recently, TMR elements were introduced as a new type of magnetoresistive sensor for industrial applications, constructed as a magnetic multilayer film material. TMR magnetic field sensing elements exhibit a greater change in resistivity, as a function of applied magnetic field induction, than that of previously developed magnetoresistance technologies, AMR and GMR. The term Magnetic Tunnel Junction is used to refer to a TMR sensing element. This talk will describe the structure, operation and fabrication process for TMR and contrast it with other magnetic sensors. Applications beyond the Hard Disk Drive area will also be described.
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