Researchers spin out smaller electronics than ever before
- 23 March, 2007 11:05
A research team of electrical and computer engineers in the U.S. is taking a new approach to electronics that harnesses the spin of an electron to store and process information. Dubbed 'spintronics', the new technology is expected to one day form a basis for the development of smaller, smarter, faster devices.
Current day electronics are predominantly charge-based; that is, electrons are given more or less electric charge to denote the binary bits 0 and 1. Switching between the binary bits is accomplished by either injecting or removing charge from a device, which can, in more resource-intensive applications, require a lot of energy.
"This [energy consumption] is a fundamental shortcoming of all charge based electronics," said lead researcher Supriyo Bandyopadhyay, a professor of Electrical and Computer Engineering at Virginia Commonwealth University.
Spin-based electronics supersede the problem of energy consumption by encoding the binary bits 0 and 1 in the direction that an electron spins in relation to an external magnetic field. This method requires less energy, since switching between the binary states does not require any physical movement of the electron and is achieved simply by changing its orientation.
"The spin of an electron is like a tiny magnet with an associated direction of the magnetic moment, [which] can have only two stable directions: parallel to the external magnetic field or anti-parallel to the magnetic field," Bandyopadhyay explained.
"Since the major obstacle to continued progress in electronics is excessive energy dissipation during switching, spin based electronics obviously can steal a march over charge based electronics," he said.
Storing information in this manner may sound fairly straightforward in theory. In the real world, however, there exist stray magnetic fields from a variety of sources, such as other electronic devices. In time, these fields are known to break down the direction of an electron's spin in a process known as 'spin relaxation', leading to an eventual loss of information.
To be effective in a computing device, Bandyopadhyay said the spin relaxation time should be at least 10,000 times longer than the time scale over which data stored in the device changes, which will allow most errors caused by spin relaxation to be fixed by appropriate software tools.
Achieving an acceptable level of spin relaxation has previously posed a problem for researchers. However, in their latest study, Bandyopadhyay and his research team have use of organic semiconductors to achieve spin relaxation times of up to one second, which is about 1,000 times longer than that of previous systems.
"In today's laptop computers, the clock period [time scale over which stored data changes] is no longer than one-billionth of a second," Bandyopadhyay said. "Therefore, if the spin relaxation time is 1 second, we have achieved a relaxation time that is 1 billion times longer than the clock period ... [which] is more than adequate."
Currently, spintronics-based memory chips are being used in memory marketed by Texas-based Freescale Semiconductors, as well as data retrieval devices like those in Apple's iPods. The technology has not yet been incorporated in computing circuitry in any major way; however, with his new findings, Bandyopadhyay expects this to change within the next decade.