| Magnonic crystals can artificially control the transmission of spin waves,so they can be used to construct a new generation of spintronic devices and have wide application prospects in the field of microwave technology.Compared with artificial materials such as photonic crystals and phonon crystals,the main feature of magnonic crystals is that the frequency bandgap can be further controlled by applying an external magnetic field,and the information can be transmitted and processed without charge movement by using the spin wave to encode information.This greatly reduces power consumption and improves device integration.Therefore,it is of great importance to study the band structure of magnonic crystals and how to artificially regulate the frequency bandgap.In this paper,the frequency bandgap of one-dimensional magnonic crystals is studied by using a self-built microscopic Brillouin Light Scattering system.The width of the frequency bandgap is artificially controlled by changing the lattice constant,and DMI is uesd to generate an additional frequency bandgap.The main contents of the paper are summarized as follows:First,a microscopic Brillouin light scattering system is constructed.Brillouin Light Scattering(BLS)is a very simple and effective method to measure the band structure of the spin wave in magnonic crystals,because the propagation characteristics of the spin wave in magnonic crystals are determined by its band structure.Therefore,we built up a backscattering Brillouin Light Scattering system,and then further optimised the external optical path and added the microscopic imaging system,integrated the functions of spatial resolution and wavevector resolution,and realised the test of magnonic crystals.Second,a controllable fabrication method for magnonic crystals with interfacial DMI is provided.Ir/Fe/Pt films were grown by magnetron sputtering instrument,and then combined with ion etching,electron beam lithography and other technical means to ensure the continuity of the magnetic layer,and realize the periodic alternating arrangement of structures with saturation magnetization of 1563 emu/cm3 and 620 emu/cm3 respectively.The 1D periodic magnonic crystal of DMI with periodic existence has been successfully fabricated.Third,it realizes the artificial regulation of the band width.The self-built micro BLS is used to test the magnonic crystals with different lattice constants and the frequency bandgap is obtained,which realizes the control of the frequency band gap.It is found that with the increase of lattice constant,the band gap width gradually decreases.Moreover,by introducing a periodic DMI with a size of 0.647 mJ/m2 into the magnonic crystals,the frequency bandgap width is increased.The existence of DMI leads to non-reciprocity in the spin wave propagation.Therefore,the frequency bandgap width of the spin wave propagating along the upper and lower surfaces of the magnetic layer is different.The frequency bandgap width of the spin wave corresponding to the anti-Stokes peak is 0.45 GHz higher than that of the spin wave corresponding to the Stokes peak.Therefore,the additional frequency bandgap width generated by DMI is 0.45 GHz. |
