Spin-WAve Nanochannels for reprogrammable logic GATEs – SWANGATE

SWANGATE is an ambitious project which aims to develop a new approach for magnonic devices at the nanometer scale. The International Technology Roadmap for Semiconductors has already identified Spin Wave based Devices (SWD) as an alternative to CMOS technology for logic devices. SWD is a type of magnetic logic devices exploiting collective spin oscillations (spin waves) for information transmission and processing. The interest of this emerging approach lies in its scalability required to handle the ever-increasing amount of data generated by our information and communication society. However the standard approach for SWD suffers several drawbacks regarding miniaturization and does not offer the possibility to address the field of reprogrammable logic devices, a cornerstone for Information and Communication Technologies. The purpose of the SWANGATE project is to investigate a new route to achieve scalable and reprogrammable SWD.

The original approach of SWANGATE consists in using magnetic Domain Walls (DW) as a wave guide for Spin Waves (SW). Partner IEF has demonstrated by the mean of micromagnetic simulations that it is possible to excite SW modes localized only in DW without exciting modes in magnetic domains. After a first demonstration of the concept with in-plane magnetized thin films, the project will focus on perpendicularly magnetized systems. Because DW width in perpendicular media can be fine-tuned below 10 nm with appropriate material choices, the resulting device is naturally sub-micrometer size. Moreover the IEF partner has shown theoretically the possibility to use “shaped” DWs such as a bend to guide SW in non-straight geometries which is crucial for any practical use.

The first part of the project will be devoted to the experimental demonstration of the possibility to efficiently generate and detect SW modes hosted by DW. This goal will be achieved by the means of different experimental techniques. Brillouin Light Scattering spectroscopy and electrical methods such as inductive Propagating Spin Wave Spectroscopy will be used to access the dispersion relation of the different SW modes. The characteristics of the measured SW modes will be compared to theoretical calculations and numerical simulations. The comprehension that will result from this study will allow us to optimize both the media and excitation-detection schemes for Domain Wall Channeled Spin-Waves (DWCSW). This part represents the first step toward nanometer scale SWD. The second part of the project addresses the core issues related to reprogrammability. Indeed, non-volatile logic devices reprogrammable on demand are highly desirable for massive data treatment. Because SWD hold great promise to be used in future information processing, the objective of this part is to demonstrate the possibility to realize a reprogrammable logic device using DWCSW. Indeed, by shaping and re-shaping the magnetic domain pattern we can design on-the-fly the waveguide form and therefore the SWD functionality. Beyond usual ways to manipulate the DW we also propose to use magneto-optical techniques such as all-optical switching to gain a full control of the DW pattern. This allows creating much more sophisticated waveguide structures, opening the path to nanometer scale reprogrammable SWD.

In conclusion, our approach addresses the key issues faced by SWD applications for handling the exponential growth of data to process. The new SWD concept we propose lies at the intersection of spintronics, nanomagnetism and opto-magnetism. The SWANGATE consortium gathers the required expertise, including SW & DW physics, material science engineering, and micromagnetic modelling in order to address the multiple research fields involved. The merging of these different techniques, in addition to the original DWCSW concept, makes our proposal innovative and ambitious, with the strong potential to place magnonic devices at the heart of the future information processing technologies.