Programmable Integrated Magneto-Phononic Circuits

Phonons, the quasi-particles of sound waves, represent an indispensable resource in modern communication technologies because of their universal coupling to literally any other system. Moreover, phonons propagate with moderate velocities which are approximately 100000- times slower than the speed of light. This enables miniaturization of gigahertz frequency devices to the size of a chip. Magnetic systems exhibit spin-wave excitations in exactly the same frequency domain and, thus, are ideally suited to couple to sound waves via magnetostriction. In this project, we develop highly integrated programmable and scalable circuits, in which the propagation of phonons can be manipulated and even programmed by precisely engineered magnetic thin films. To this end, we bundle our complementary theoretical and experimental expertise and develop a complete toolbox of circuit elements for the design of integrated magneto-phononic circuits. This project addresses three major objective and research questions which are crucial for fundamental understanding and application: (1) Development of theoretical and experimental methods to model, design and fabricate magneto-phononic integrated circuits. To this end we (i) unify modeling methods for magnetic and phononic systems on a common platform, (ii) combine nanofabrication techniques of phononic circuits and magnetic thin films, and (iii) validate the designed and fabricated magneto-phononic circuits by radio frequency spectroscopy. (2) Investigation of the magneto-phononic coupling between magnetic thin films and dispersion-engineered phononic waveguides. (3) Realization of integrated and programmable prototype devices, for instance isolators and circulators for radio frequency applications. At each stage of the project, new theoretical approaches and experimental techniques will be developed, which not only address important fundamental questions. Moreover, it lays the foundation for novel magneto-phononic circuits. Their vast potential promise even more far- reaching applications in combination with for instance optically addressable spin systems or quantum emitters.