Micromagnetic Simulation of Nanomagnet Logic Devices
Nanomagnet Logic (NML), also known as Magnetic Quantum-Dot Cellular Automata, emerges as a promising candidate for novel “beyond CMOS” technologies.
In this new paradigm, single-domain nanomagnets represent logic values, and digital computing is realized by means of their magnetic interactions, providing benefits such as non -volatility, high integration density and low power dissipation.
A fully functional NML system is composed of an electronic / magnetic interface serving as input, field-coupled nanomagnets which store and process binary data, a clocking structure to control the information flow, and an electronic readout mechanism.
In this research group we perform computational studies on NML devices, based on materials with out-of-plane anisotropy (Co/Pt).
We developed a model to describe the switching behavior of single-domain Co/Pt nanomagnets and predicted non-reciprocal coupling behavior from focused-ion-beam partially irradiated Co/Pt magnets.
We demonstrated that with non-reciprocal coupling, the information flow can be well-controlled and error-free ordering can be achieved in large-scale NML circuits.
Now we are making efforts to apply our model in more large-scale architectures.
Nanomagnet Fabrication Using Nanoimprinting, Electrodeposition and Nanotransfer
Nanoimprinting (NIL) and nanotransfer printing (nTP) are a new non-conventional fabrication techniques for nano structures.
Compared to Electron Beam Lithography (EBL) nanoimprinting and nanotransfer printing are faster (they can produce large areas in a fraction of the time), cheaper (the overall cost for the equipment is comparatively low), and scalable (they are more suitable for large scale industrial fabrication.)
One of the main focusesof our work is to use nanoimprinting and nanotransfer printing for fabricating NML structures.
The work consists of optimizing the fabrication process and analyzing the fabricated devices for magnetic coupling and logical operations.
We use permalloy, an alloy of Nickel and Iron (80% Ni and 20% Fe), as the magnetic material.
After pattern fabrication using either NIL or nTP, we deposit the permalloy on the patterned substrate using eletrodeposition from an electrolytic solution.
Alternatively, we transfer directly on a given substrate permalloy nanostructures previously evaporated on a patterned stamp.
Ju, X. et al. Nanomagnet Logic from Partially Irradiated Co/Pt Nanomagnets. IEEE Transactions on Nanotechnology, 11, 97–104 (2012). doi: http://dx.doi.org/10.1109/TNANO.2011.2157974
Becherer, M et al. On-chip Extraordinary Hall-effect sensors for characterization of nanomagnetic logic devices. Solid-State Electronics 54 (2010). doi: http://dx.doi.org/doi:10.1016/j.sse.2010.04.011