Out for a spin

May 1, 2014 by Julianna Fleming
This article appeared in Berkeley Engineer magazine, Spring 2014

Sayeef SalahuddinElectrical engineering and computer sciences professor Sayeef Salahuddin (Photo by Daniel McGlynn)Semiconductor-based transistors, the on-off switches that direct electricity flow and form a computer’s nervous system, consume greater chunks of power at increasingly hotter temperatures as processing speeds grow. A decade of research shows that magnets might be an alternative because they require far less energy when switching. However, the power needed to generate the magnetic field has negated much of the energy savings. But new work by Berkeley researchers could transform modern electronics by making nanomagnetic switches a viable replacement for the conventional transistors found in all computers. The researchers exploited a so-called Spin Hall effect by using nanomagnets placed on top of tantalum wire and then sending a current through the metal. When the current is sent through tantalum’s atomic core, the metal’s physical properties naturally sort the electrons to opposing sides based on their direction of spin. This creates the polarization to switch magnets in a logic circuit without needing a magnetic field. Electrical engineering and computer sciences professor Sayeef Salahuddin, graduate student Debanjan Bhowmik and Long You, a research scholar, co-authored the study.