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Next generation of computing in a spin

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Research at Cambridge University in the UK may have brought the next generation of computers one step closer. Physicists at the Cavendish Laboratory, the University of Cambridge’s Department of Physics, have obtained new insights into spintronics, thought by many to be the successor technology to the transistor. 

Spintronics, which exploits the electron’s magnetic moment or ‘spin’, could radically change computing due to its potential of high-speed, high-density and low-power consumption. The new research show how to make the process more efficient. 

Over the past half-century or so, the semiconductor industry has successfully continued to shrink the size of transistors used in computers and other electronic equipment. Intel co-founder Gordon E. Moore formulated what has now come to be known as 'Moore's Law' as long ago as 1965, when he noted that the number of transistors that could be placed inexpensively on an integrated circuit had doubled every year between 1958 and 1965, and predicted that the trend would continue. 

But the end of that trend — the moment when transistors are as small as atoms, and cannot be shrunk any further — is expected as early as 2015. Consequently, researchers are trying out new concepts for electronics that could allow the growth of computing power to continue.

Spintronics attempts to develop a spin-based electronic technology to replace the charge-based technology of semiconductors. Spin-based electronics took a great step forward with the discovery in 1988 of giant magnetoresistance (GMR). The discovery of GMR brought about a breakthrough in gigabyte hard disk drives and was also important in the development of portable electronic devices such as the iPod. 

One of the unique properties in spintronics is that spins can be transferred without the flow of electric charge currents. This 'spin current' can transfer information without generating heat in electric devices. The major remaining obstacle to a viable spin current technology is the difficulty of creating a volume of spin current large enough to support current and future electronic devices. 

The new Cambridge research in close collaboration with Professor Sergej Demokritov's group at the University of Muenster, Germany, have, in part, addressed this issue. In order to create enhanced spin currents, the researchers used the collective motion of spins called spin waves (the wave property of spins). By bringing spin waves into interaction, they have demonstrated a new, more efficient way of generating spin current.

Dr Hidekazu Kurebayashi, from the Microelectronics Group at the Cavendish Laboratory, said: 'You can find lots of different waves in nature, and one of the fascinating things is that waves often interact with each other. Likewise, there are a number of different interactions in spin waves. Our idea was to use such spin wave interactions for generating efficient spin currents.'

According to their findings, one of the spin wave interactions (called three-magnon splitting) generates spin current ten times more efficiently than using pre-interacting spin-waves. Additionally, the findings link the two major research fields in spintronics, namely the spin current and the spin wave interaction.