A Model Spin Amplifier

Circuit miniaturization has continued to revolutionize the speed and diverse capabilities of modern electronic systems. At present, though, the increase in device-packing density onto microelectronics chips and the associated problem of managing heat dissipation is becoming an issue in limiting performance. Using the spin of the electrons in place of traditional charge flow is therefore being explored as a possible route to circumvent that performance roadblock. The transistor is the present building block of microelectronics. However, the equivalent spin amplifier, or spin transistor, would require a room-temperature magnetic semiconductor. Because all the true magnetic semiconductors to date have been limited to cryogenic temperatures, the prospect of developing a practical spin transistor seems some way off. Breaking the process down into three stages—spin detection, signal amplification, and spin filtering of that amplified signal—Acremann et al. suggest an alternative method that may provide a spin amplifier using a sequence of electrical and magnetic field pulses to manipulate the magnetization of a patterned ferromagnetic layer. Such an engineered spin amplifier using presently available materials may bring forward the development of spintronics, and with it the additional functionality of having sensing, memory storage, and logical operation in a single device. — ISO