Shape key to strong sensors

Researchers from the University of Cambridge in England and the Los Alamos National Laboratory have found a possible explanation for why a pair of semi conducting compounds -- mixes of silver and selenium or tellurium -- are strong magnetic sensors over a wide range of magnetic field strengths.

More importantly, they showed that the materials' sensitivity has to do with the materials' structure and can be modeled using a random array of disk-shaped resistors. Resistors slow electrical current.

This geometric model of magnetoresistance could be used to produce cheap, precise strong-magnetic-field sensors that are largely unaffected by temperature and that show a tailor-made, linear response to the strength of a magnetic field; such sensors could be built from ordinary materials and could operate over a large range of magnetic fields, according to the researchers.

Strong magnetic field sensors are used in medical imaging systems, industrial monitors and laboratory equipment. Other types of magneto resistance devices, however, are overwhelmed by strong magnetic fields.

It is also possible that the model could be adapted to produce the ultra-low field sensors needed to read data from magnetic media including computer hard disks, according to the researchers.

The researchers' methods could be used to make high-field magnetic sensors in one to two years, according to the researchers. The work appeared in the November 13, 2003 issue of Nature.