Development of Ultrasensitive Magnetic Field Sensor


Philip Wing-Tat PONG


Magnetic field sensors have important applications over the past fifty years in many different technological areas, ranging from data storage to biomedical applications. A magnetic sensor provides reliable, low-cost solutions for a variety of measurement of rotational speed, angle, linear displacement, electric current, and Earth magnetic field detection for compass and navigation applications. Nowadays, technology offers the possibility of measuring magnetic field from high field (tens of Tesla) to low field (nanoTesla, 10-9T). Low field sensing is of particular interest because it provides a promising route to realize faster computation with magnetic RAM and larger storage with higher density of magnetic information storage.


With the aim of achieving extremely low field detection, we are developing technology to develop a ultrasensitive magnetic field sensor with sensivitiy down to picoTesla (10-12T). Tunneling magnetoresistance (TMR) is the next generation of the giant magnetoresistance (GMR) wherein the electric current, instead of flowing in plane with the magnetic layers separated by a non-magnetic layer, flows perpendicular through the magnetic layers sandwiching an insulating layer. The TMR phenomenon enhances the magnetoresistance ratio up to 400% at room temperature. A device exhibiting TMR is called a magnetic tunneling junction (MTJ). A MTJ with its magnetic properties of the magnetic layers properly optimized is a promising candidate to actualize the mission of ultralow field detection.




Philip Wing-Tat PONG

Building 223 / Room B148


Mentorís name: William Egelhoff


Metallurgy Division

Materials Science and Engineering Laboratory

Mail Stop: 8552


Telephone #: 301-975-8876

FAX #: 301-975-4553



Sigma Xi member: No

Category: Physics