mCell Model 1.0.1

By David M. Bromberg1, Daniel H. Morris1

Carnegie Mellon University

This model is a hybrid physics/empirical compact model that describes digital switching behavior of an mCell logic devices, where a write current moves a domain wall to switch the resistance of a magnetic tunnel junction between stable states.

Listed in Compact Models | publication by group NEEDS: New Era Electronic Devices and Systems

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Version 1.0.1 - published on 19 Jan 2015 doi:10.4231/D3CR5ND3Q - cite this

Licensed under NEEDS Modified CMC License according to these terms


We present a hybrid physics/empirical compact model for the mCell device [1,2]. The mCell is a four terminal magnetic device with isolated write- and read-paths, designed to enable all-magnetic logic and memory circuits. A direction of write current through the write-path moves a domain wall, thereby setting the magnetization of the device to orient in one of two stable directions. The programmed state is read out with magnetic tunnel junctions in an electrically-isolated but magnetically-coupled read-path.


This model is intended for use in digital circuit simulations only, ideally with sub-50 ns current pulses. The domain wall velocity is calculated based on a first-order model of domain wall dynamics under spin-transfer torque (as described in the manual). Additional behavior, including pulse width-dependent current thresholds for domain wall depinning, is introduced empirically based on results of micromagnetic simulations of the Landau-Lifshitz-Gilbert equation.

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Minor update to address all items in wishlist:

- Removed unused beta term (explained in manual)
- Removed an unnecessary test on whether or not an initial state is provided (a default state is always given)
- Avoided use of @(initial_step)
- Added additional precision to e_charge constant based on NIST 2010 standards, removed include statement to constants.vams
- Removed domain_wall_gnd nanokinematic node and referenced all branches to global GND