May 9 2019
Logic and memory devices, such as the hard drives in computers, currently apply nanomagnetic mechanisms to store and control information. In contrast to silicon transistors, which have major efficiency boundaries, they do not need energy to preserve their magnetic state: Energy is required just for reading and writing information.
One technique of exploiting magnetism uses electrical current that conveys spin to write information, but this typically includes flowing charge. Since this generates heat and energy loss, the costs can be huge, especially in the case of large server farms or in applications such as artificial intelligence, which require huge amounts of memory. Spin, however, can be conveyed without a charge with the help of a topological insulator – a material whose interior is insulating but that can aid the flow of electrons on its surface.
In a recently published Physical Review Applied paper, scientists from New York University promote a voltage-controlled topological spin switch (vTOPSS) that needs just electric fields, instead of currents, to shift between two Boolean logic states, significantly decreasing the heat produced and energy used. The team consisted of Shaloo Rakheja, an assistant professor of electrical and computer engineering at the NYU Tandon School of Engineering, and Andrew D. Kent, an NYU professor of physics and director of the University’s Center for Quantum Phenomena, along with Michael E. Flatté, a professor at the University of Iowa.
Rakheja uses a basic analogy to explain the effect of switching between two states more successfully.
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. 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.
Shaloo Rakheja, Assistant Professor of Electrical and Computer Engineering, Tandon School of Engineering, NYU
While heterostructure devices similar to theirs, made up of a magnetic insulator and topological insulator, are still somewhat slower than silicon transistors, vTOPSS boosts functionality and circuit design potentials, as it has in-built logic and non-volatile memory. “This is ultimately a matter of user experience and added features,” Rakheja says.
As vTOPPS will decrease dependence on cloud memory, it also has the prospect of ensuring the safety of computing, as hackers will have more trouble gaining entry into a system’s hardware. Following steps will involve additional optimization at the materials and design level to enhance the speed of switching, as well as creating prototypes.
The scientists’ efforts were backed by the National Science Foundation’s Materials Research Science and Engineering Centers (MRSEC), and their paper, “Voltage-controlled topological spin switch for ultralow-energy computing-performance modeling and benchmarking,” can be read at journals.aps.org.