Self Biased Integrated Magnonic Device

TL;DR

This paper introduces a compact, fully integrated magnonic device on silicon that achieves tunable spin wave excitation without external magnetic fields, advancing magnonics for future telecommunication technologies.

Contribution

It presents the first standalone, all-electric, tunable magnonic device with integrated flux concentrators and permanent magnets on silicon, eliminating the need for bulky external magnetic bias fields.

Findings

Device operates in 3-8 GHz frequency range.

Achieves phase shift tuning up to 120 degrees.

Tunable bias field from 20.5 mT to 11 mT by adjusting flux concentrator distance.

Abstract

In the race towards "beyond 6G" telecommunication platforms, magnonics emerges as a promising solution due to its wide tunability within the FR3 band (7-24 GHz). So far, however, the need for an external magnetic bias field to allow the coherent excitation of spin waves has been a major bottleneck. Conventional bulky electromagnets are power-intensive and challenging to integrate on-chip, restricting magnonic applications largely to academic research. Here, we present the first demonstration of a standalone, tunable magnonic device featuring all-electric input and output, fully integrated on a silicon substrate with a compact footprint of 100 x 150 $\mu$m. The device consists of a CoFeB waveguide equipped with two radio frequency antennas, flanked by a symmetric configuration of T-shaped magnetic flux concentrators and rectangular SmCo permanent micromagnets. By varying the distance D between the flux concentrators and the permanent magnets from 0 to 12 $\mu$m, the transverse bias field can be tuned from 20.5 mT to 11 mT, respectively. This variation directly modulates the dispersion relation of Damon-Eshbach spin wave modes in the CoFeB waveguide. In these proof-of-concept devices, the spin wave frequency band ranges from 3 to 8 GHz, with precise phase shift tuning of up to 120 degrees at 6 GHz achieved by varying D within the 0-8 $\mu$m range. The operational frequency band could even be pushed to higher frequencies through optimized micromagnet engineering.