  All-spin logic device (ASLD) has attracted increasing interests as one of the
most promising post-CMOS device candidates, thanks to its low power,
non-volatility and logic-in-memory structure. Here we investigate the key
current-limiting factors and develop a physics-based model of ASLD through
nano-magnet switching, the spin transport properties and the breakdown
characteristic of channel. First, ASLD with perpendicular magnetic anisotropy
(PMA) nano-magnet is proposed to reduce the critical current (Ic0). Most
important, the spin transport efficiency can be enhanced by analyzing the
device structure, dimension, contact resistance as well as material parameters.
Furthermore, breakdown current density (JBR) of spin channel is studied for the
upper current limitation. As a result, we can deduce current-limiting
conditions and estimate energy dissipation. Based on the model, we demonstrate
ASLD with different structures and channel materials (graphene and copper).
Asymmetric structure is found to be the optimal option for current limitations.
Copper channel outperforms graphene in term of energy but seriously suffers
from breakdown current limit. By exploring the current limit and performance
tradeoffs, the optimization of ASLD is also discussed. This benchmarking model
of ASLD opens up new prospects for design and implementation of future
spintronics applications.
