Researchers have made an important advance in the emerging field of spintronics that may one day usher in a new generation of smaller, smarter, faster computers, sensors and other devices, according to findings reported in today’s issue of the journal Nature Nanotechnology.
Spintronics is concerned with using the “spin” of an electron for storing, processing and communicating information.
The research team of electrical and computer engineers from the Virginia Commonwealth University’s School of Engineering and the University of Cincinnati examined the “spin” of electrons in organic nanowires, which are ultra-small structures made from organic materials, explained a university statement. These structures have a diameter of 50 nanometers, which is 2,000 times smaller than the width of a human hair. The spin of an electron is a property that makes the electron act like a tiny magnet. This property can be used to encode information in electronic circuits, computers and virtually every other electronic gadget, explains the statement.
“In order to store and process information, the spin of an electron must be relatively robust. The most important property that determines the robustness of spin is the so-called spin relaxation time, which is the time it takes for the spin to “relax.” When spin relaxes, the information encoded in it is lost. Therefore, we want the spin relaxation time to be as long as possible,” said corresponding author Supriyo Bandyopadhyay, PhD, a professor in the department of electrical and computer engineering at the VCU School of Engineering.
“Typically, the spin relaxation time in most materials is a few nanoseconds to a few microseconds. We are the first to study spin relaxation time in organic nanostructures and found that it can be as long as a second. This is at least 1,000 times longer than what has been reported in any other system,” Bandyopadhyay said.
The team fabricated its nanostructures from organic molecules that typically contain carbon and hydrogen atoms. In these materials, spin tends to remain relatively isolated from perturbations that cause it to relax. That makes the spin relaxation time very long.
The VCU-Cincinnati team was also able to pin down the primary spin relaxation mechanism in organic materials, which was not previously known. Specifically, the group found that the principal spin relaxation mechanism is one where the spin relaxes when the electron collides with another electron, or any other obstacle it encounters when moving through the organic material. This knowledge can allow researchers to find means to make the spin relaxation time even longer.
“The organic spin valves we developed are based on self-assembled structures grown on flexible substrates which could have a tremendous impact on the rapidly developing field of plastic electronics, such as flexible panel displays,” said Marc Cahay, PhD, a professor in the department of electrical and computer engineering at the University of Cincinnati. “If the organic compounds can be replaced by biomaterials, this would also open new areas of research for biomedical and bioengineering applications, such as ultra-sensitive sensors for early detection of various diseases.”
The work is supported by the U.S. Air Force Office of Scientific Research and the National Science Foundation.