PORTLAND, Ore. — Spintronics harnesses the magnetic polarization of electrons to encode and store information rather than the presence or absence of charge. Passing current through a ferromagnetic material can encode electrons with a known spin state--either up or down--but detecting the magnetic moment of the individual electrons after they have been used to process information is extremely difficult.

Rensselaer Polytechnic Institute (RPI, Troy, N.Y.) researchers now believe that carbon nanotubes can be used to detect such nanoscale magnetic states by changing their conductance. They demonstrated the change by embedding tiny nanoparticles of magnetic cobalt into multi-walled carbon nanotubes.

The researchers furthermore claim that their findings could enable spintronics applications, nanoscale storage devices and ultra-sensitive conductance detectors.

RPI professors Swastik Kar and Saroj Nayak embedded clusters of cobalt atoms measuring from one to 10 nanometers in diameter into the walls of carbon nanotubes, then showed how they could be used to detect trace amounts of magnetism in nanoscale materials. The electrical conductance of the nanotubes was shown to be sufficiently sensitive to detect the magnetic state of the tiny cobalt domains.

Carbon nanotube electronics capable of detecting magnetic degrees of freedom could speed the development of spintronics applications, Kar and Nayak said.

Funding was provided by RPI and the New York State Interconnect Focus Center.