Interconnect analysis in spin-torque devices: performance modeling, optimal repeater insertion, and circuit-size limits

Shaloo Rakheja and Azad Naeemi
Georgia Institute of Technology


A spin-torque device may be considered as the basic building block of an information processing system utilizing electron spin as the state variable. In this paper, interconnection aspects of spin-torque circuits are analyzed and their performance and energy dissipation are compared against those of their conventional electrical counterparts at the 7.5nm technology node. Spin circuits with two flavors of nanomagnet dynamics are considered: (a) nanomagnets with complete spin-torque assisted switching and (b) nanomagnets with mixed-mode switching utilizing Bennett clocking. The interconnect in the spin-torque logic is assumed to be implemented with graphene nanoribbons. This paper presents the first comprehensive circuit- and system-level interconnect analysis for the two major detection mechanisms using physical models for spin injection and transport in graphene nanoribbons and physical models for nanomagnet switching dynamics. In addition, optimal repeater insertion requirements to minimize the delay of spin interconnects have been obtained for the first time in this paper. The results offer important metrics for spin- based interconnects to outperform conventional electrical interconnects.