News Article
State University Of New York (SUNY) At Buffalo Engineering Scientists Report
State University of New York (SUNY) at Buffalo engineering scientists report
a ballistic magnetoresistance effect of 3150% at room temperature (Physical
Review B, July 1, 2002). The researchers used electrodeposited nickel
nanocontacts to produce devices with switching fields of a few hundred
oersteds. The effect compares with the giant magnetoresistance (GMR) effect
used in hard disk drives of less than 100%. One of the researchers, Harsh
Deep Chopra, predicts that BMR devices could create storage capacities of a
terabit per square inch. The detector could also be used in scientific
studies of magnetism and to enhance the resolution of scanning probe
microscopes.
The BMR sensor has just a cluster of ferromagnetic atoms (nanocontact)
connecting two electrodes. The term "ballistic" means that the sample is so
small that electrons pass through without scattering in zero field (mean
free path greater than the sample size). With a field applied, the
scattering is due to magnetism and not the properties of the material.
Spin-polarised electrons scatter more or less (with greater or less
resistance) depending on the magnetisation state of the nanocontact.
connecting two electrodes. The term "ballistic" means that the sample is so
small that electrons pass through without scattering in zero field (mean
free path greater than the sample size). With a field applied, the
scattering is due to magnetism and not the properties of the material.
Spin-polarised electrons scatter more or less (with greater or less
resistance) depending on the magnetisation state of the nanocontact.
