This paper proposes a novel logic device (SkyLogic) based on skyrmions that are magnetic vortex-like structures having low depinning current density and are robust to defects. A charge current sent through a polarizer ferromagnet (P-FM) nucleates a skyrmion at the input end of an intragate FM interconnect with perpendicular magnetic anisotropy (PMA-FM). The output end of the PMA-FM forms the free layer of an magnetic tunnel junction (MTJ) stack. A spin Hall metal (SHM) is placed beneath the PMA-FM. The skyrmion is propagated to the output end of the PMA-FM by passing a charge current through the SHM. The resistance of the MTJ stack is low (high) when a skyrmion is present (absent) in the free layer, thereby realizing an inverter. A framework is developed to analyze the performance of the SkyLogic device. A circuit-level technique is developed that counters the transverse displacement of skyrmion in the PMA-FM and allows the use of high current densities for the fast propagation. The design space exploration of the PMA-FM material parameters is performed to obtain an optimal design point. At the optimal point, we obtain an inverter delay of 434 ps with a switching energy of 7.1 fJ.
Bibliographical noteFunding Information:
Manuscript received October 26, 2018; revised January 1, 2019; accepted February 6, 2019. Date of publication March 5, 2019; date of current version March 22, 2019. This work was supported in part by C-SPIN, one of the six SRC STARnet Centers, sponsored by MARCO and DARPA, and in part by the Louise T. Dosdall Fellowship from the University of Minnesota. The review of this paper was arranged by Editor W. Tsai. (Corresponding author: Meghna G. Mankalale.) The authors are with the Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455 USA (e-mail: firstname.lastname@example.org; email@example.com; firstname.lastname@example.org; email@example.com).
- Design space exploration