Regulation Mechanism Of Spin-Wave Transistor And Its Realization

In recent years,with the iteration of charge-based transistors on performance parameters such as energy consumption,physical size and computing time slows down gradually,the upgrade and development of the integrated circuit industry has encountered a bottleneck.Therefore,as a kind of information device under the concept of“beyond CMOS”,the spin-wave transistor comes into being.Different from charge-based transistors,spin-wave transistors resorts to bosons（magnons,the quantum elementary of spin waves）as the collective excitation form for computation.Benefits from this characteristic,spin-wave transistors can be realized by many novel physical effects,and only rely on electron spin interactions in the process of transmitting or processing information,therefore spin-wave transistors have extremely low power consumption.In addition,spin-wave transistors have the advantages of small size,ease of reconfigurability,and a wide and adjustable frequency range,which is more promising than the optical transistor or the acoustic transistor.Based on the concept of magnon integrated circuits or magnon-electron hybrid integrated circuits,this thesis proposes and is able to realize a variety of important functions of spin-wave devices,including the magnetic field-free spin-wave waveguide,high-efficiency spin-wave signal intensifier,multifunctional spin-wave transistor and low-power dissipation spin-wave logic gate.The functional perfection of a single spin-wave information device and the implementability of spin-wave circuits are improved effectively.The contents of this thesis are as following:1.The transmission of spin waves without an external magnetic field is achieved for the first time in micrometer-thick ferrimagnetic insulating bismuth-doped thulium iron garnet(Bi Tm₂Fe₅O₁₂,Bi:Tm IG)films possessing perpendicular magnetic anisotropy.Through all-electrical broadband spin-wave spectroscopy,the spin-wave attenuation length and group velocity are determined to be 20.5μm and 4.90 km/s,respectively,under zero magnetic field.The spin wave attenuation length achieved in this study is the highest among existing schemes for spin-wave transmission without an external magnetic field.This research is expected to significantly reduce the redundancy of magnetic devices and circuit systems,thereby laying the foundation for the development of spin-wave computing systems that are both charge-free and field-free.2.A novel and efficient low-k（k is the wave vector）spin-wave detection signal enhancer is proposed,with the signal amplitude increased up to 2.75 times the original amplitude.The study shows that metals with high conductivity and low magnon dissipation efficiency can shield the precessing magnetic moments on the surface of yttrium iron garnet(Y₃Fe₅O₁₂,YIG)film,significantly accelerating the propagation of spin waves.The group velocity of spin waves can be increased from 55 km/s to 133 km/s.This increase in group velocity allows the spin-wave detection antannas to receive more magnon energy per unit time,thereby achieving the effect of spin-wave detection signal enhancement.This work provides a practical,strong and widely applicable method for achieving spin-wave manipulation and low-loss transmission.3.A thermal phonon-gated reconfigurable spin-wave transistor is developed.By utilizing the magnon-phonon coupling effect in a ferrimagnetic insulating lanthanum-doped yttrium iron garnet(La_0.03Y_2.97Fe₅O₁₂,La:YIG)film,the transistor can perform three functions in different power regions:linear phase shifting,significant signal amplification,and complete signal cut-off.The contributions of spin-wave dispersion relation shifting,longitudinal Spin-Seebeck effect,and magnon-magnon interactions induced by non-equilibrium thermal magnon injection to the functionalities of the spin-wave transistor are elucidated,respectively.This reconfigurable spin-wave transistor offers a new avenue for realizing high-efficiency magnonic integrated circuits.4.A low-power spin-wave XOR logic gate based on the Mach-Zehnder interferometer is designed and fabricated using microelectronic fabrication techniques.This prototype device only requires a temperature difference of 2.9 K between the waveguides of the interferometer to achieve logic switching.Calculations suggest that,with the existing data support,the logic gate can be scaled down to an area of 0.1 um²,which is on the same order of magnitude as that of a 7 nm-CMOS inverter,and with a power consumption of 0.13 aJ,which is two to three orders of magnitude lower than that of a 7 nm-CMOS inverter.The realization of this spin-wave logic gate is a critical step towards spin-wave logic circuits.