Voltage-Controlled Topological Spin Switch for Ultralow-Energy Computing: Performance Modeling and Benchmarking

A voltage-controlled topological spin switch (VTOPSS) that uses a hybrid topological insulator-magnetic insulator multiferroic material is presented that can implement Boolean logic operations with sub-10-aJ energy per bit and an energy-delay product on the order of 10-26 J s. The device uses a topological insulator, which has the highest efficiency of conversion of 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. We present the theory of operation of the VTOPSS, develop analytic models of its performance metrics, elucidate performance scaling with dimensions and voltage, and benchmark the VTOPSS against existing spin-based and CMOS devices. Compared with existing spin-based devices, such as all-spin logic and charge-spin logic devices, the VTOPSS offers 10-70 times lower energy dissipation and 70-1700 times lower energy-delay product. With experimental advances and improved material properties, we show that the energy and energy-delay product of the VTOPSS can be lowered to a few attojoules per bit and 10-28 J s, respectively. As such, the VTOPSS technology offers competitive metrics compared with existing CMOS technology. Finally, we establish that interconnect issues that dominate the performance in CMOS logic are relatively less significant for the VTOPSS, implying that highly resistive materials can indeed be used to interconnect VTOPSS devices.