Hybridization of Acoustic Resonance with Magnon and photON in YIG

• Applicant: Professor Dr. Georg Schmidt
• Subject Area: Experimental Condensed Matter Physics
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 490952840

New developments in telecommunication and quantum information necessitate the introduction of new materials for post CMOS technologies that offer new ultra low dissipation microwave functionalities, while remaining compatible with integration and nano-patterning. In this respect, magnetic garnets with a well-established track record of improving the performance of microwave or optical devices are prime candidates. So far the development of yttrium iron garnet (YIG) thin films for integrated solutions was hampered by the fact that high quality epitaxial growth could only be achieved on gadolinium gallium garnet (GGG) substrates. GGG, however, must be considered as a matched material for both the phonon and photon character, which thus offers an energy leakage path and as a consequence prohibits the confinement of their microwave energy within the sole YIG layer. To overcome this problem, a new process developed by the group of G. Schmidt in Halle has allowed to fabricate free standing micron-size YIG beams with high magnon life time, hereby mainly avoiding the energy leakage through the substrate. These new objects have the potential to become game-changers for high-fidelity front-end telecom components operating at GHz frequencies. Furthermore, they can provide new tools for quantum information exchange between distant qbits also operating at GHz frequencies.HARMONY will initiate a technological breakthrough by providing a viable development path for integrating the coherent and efficient interconversion of information between photon-magnon-phonon on a chip. It builds on the tripartite hybridization process inside magnetic garnets that employs nested resonances of increasing finesse. HARMONY focuses on the fabrication of suspended YIG beams to remove technological road-blocks by the following goals: i) provide an efficient scheme to excite GHz phonons by magneto-elastic effects through the co-tuning of 3 cavities; ii) improve the energy efficiency with an ultra-low loss material that is isolated from the substrate for the highest finesse and iii) implement this in an integrated on-chip device.The objective of the project HARMONY will be to evaluate within a 3 years period, how these suspended garnet structures perform as microwave transducers. The project is designed as a collaboration between the group of Spintec, Néel and Halle. The Synergy of their complementary track records will allow us to realize these ambitious goals. While coupling of magnons to microwave photons at low temperature will mainly be performed in Germany, the coupling of magnons to phonons will be performed in France. The micropatterning and YIG deposition is uniquely located in Halle while micromagnetic simulations and resonator design as well as characterization of all structures by FMR microscopy at room temperature is done at Spintec, matched by opto-mechanical surveys of the vibration pattern at Néel.

• DFG Programme: Research Grants
• International Connection: France
• Cooperation Partners: Professor Dr. Olivier Klein; Dr. Benjamin Pigeau