Magnetic-based technologies, like NanoMagnetic Logic, are gaining more interest as possible substitutes for CMOS transistors. Most logic and memory devices use nanomagnetic mechanisms to store and manipulate information. They needed energy only to read and write the information, not to maintain their magnetic state.
Another method of controlling magnetism uses an electrical current that transports spin to write information, usually involving a flowing charge. It can be enormously costly when used in large server farms or in bigger applications, like artificial intelligence, that need extensive memory. This is because it generates heat and energy loss.
However, spin can be transported without a charge using a topological insulator. A topological insulator is a material whose interior is insulating but can support the flow of electrons on its surface.
Using the same technique, the researchers from New York University introduced a voltage-controlled topological spin switch (vTOPSS). Instead of the current, an electric field is required to switch between two Boolean logic states. This could reduce the heat generated and the energy used.
The device uses a topological insulator with the highest efficiency of converting the electric field to spin torque yet observed at room temperature and a low-moment magnetic insulator that can respond rapidly to a given spin torque.
A team member, Shaloo Rakheja, an electrical and computer engineering assistant professor at the NYU Tandon School of Engineering, employs a simple analogy to explain the impact of switching between two states more effectively. “Imagine if you were preparing a recipe and had to go into a different room anytime you needed an ingredient before returning to the kitchen to add it,” she says. “It’s just as inefficient when the portions of computing hardware needed to do a calculation and the portions needed to store it are not well integrated.”
While these devices are still slightly slower than silicon transistors, vTOPSS increases functionality and circuit design possibilities, as it has integrated logic and non-volatile memory. “This is ultimately a matter of user experience and added features,” Rakheja says.
Moreover, the researchers also hope that this topological spin switch will make computing safer as it reduces the reliance on cloud memory. This is why hackers will have more difficulty accessing a system’s hardware.
Besides Shaloo Rakheja, the team comprises Andrew D. Kent, an NYU professor of physics and director of the University’s Center for Quantum Phenomena, and Michael E. Flatté, a professor at the University of Iowa.
The researchers plan to include further optimization at the materials and design level to improve the switching speed and develop prototypes.
