We theoretically investigate the propagation characteristics of spin waves in skyrmion-based magnonic crystals. It is found that the dispersion relation can be manipulated by strains through magneto-elastic coupling. ...We theoretically investigate the propagation characteristics of spin waves in skyrmion-based magnonic crystals. It is found that the dispersion relation can be manipulated by strains through magneto-elastic coupling. Especially, the allowed bands and forbidden bands in dispersion relations shift to higher frequency with strain changing from compressive to tensile,while shifting to lower frequency with strain changing from tensile to compressive. We also confirm that the spin wave with specific frequency can pass the magnonic crystal or be blocked by tuning the strains. The result provides an advanced platform for studying the tunable skyrmion-based spin wave devices.展开更多
The complex refractive indices and the dielectric function of GaN for frequencies ranging from 0.25 to 1.22THz are obtained using THz time-domain spectroscopy. The real part of the dielectric function first decreases ...The complex refractive indices and the dielectric function of GaN for frequencies ranging from 0.25 to 1.22THz are obtained using THz time-domain spectroscopy. The real part of the dielectric function first decreases from 0.25 to 0.42THz and then oscillates from 0.42 to 1.22THz, whereas the imaginary part of the dielectric function is oscillating within the whole range of frequency. The simple Drude model is extended to take into account the effect of defects on the dielectric function. The extended model is in agreement with the experimental data.展开更多
We investigate the current-driven characteristics and applications of magnetic skyrmion strings by micromagnetic simulations.Under the spin-polarized driving current,the skyrmion string presents different moving traje...We investigate the current-driven characteristics and applications of magnetic skyrmion strings by micromagnetic simulations.Under the spin-polarized driving current,the skyrmion string presents different moving trajectories in different layers due to the skyrmion Hall effect.Moreover,a series of skyrmion bobbers can be generated with a notch defect placed in the surface and the skyrmion bobbers will follow the skyrmion string.By varying the current density,the bobbers'characteristics such as number and velocity can be manipulated,which inspires us to propose a skyrmion string-based diode.In addition,an AND logic gate and an OR logic gate in the identical scheme based on the skyrmion string are proposed.AND logic and OR logic behaviors can be realized by varying the driving current densities.Our findings will contribute to further research of magnetic skyrmion strings for data storage,processing,and energy-efficient computing.展开更多
A spintronic theory is developed to study the effect of lattice distortion on the magnetic tunnel junctions(MTJs)consisting of single-crystal barrier and half-metallic electrodes.In the theory,the lattice distortion i...A spintronic theory is developed to study the effect of lattice distortion on the magnetic tunnel junctions(MTJs)consisting of single-crystal barrier and half-metallic electrodes.In the theory,the lattice distortion is described by strain,defect concentration and recovery temperature.All three parameters will modify the periodic scattering potential,and further alter the tunneling magnetoresistance(TMR).The theoretical results show that:(1)the TMR oscillates with all the three parameters;(2)the strain can change the TMR about 30%;(3)the defect concentration will strongly modify the periodic scattering potential,and further change the TMR about 50%;and(4)the recovery temperature has little effect on the periodic scattering potential,and only can change the TMR about 10%.The present work may provide a theoretical foundation to the application of lattice distortion for MTJs consisting of single-crystal barrier and half-metallic electrodes.展开更多
文摘We theoretically investigate the propagation characteristics of spin waves in skyrmion-based magnonic crystals. It is found that the dispersion relation can be manipulated by strains through magneto-elastic coupling. Especially, the allowed bands and forbidden bands in dispersion relations shift to higher frequency with strain changing from compressive to tensile,while shifting to lower frequency with strain changing from tensile to compressive. We also confirm that the spin wave with specific frequency can pass the magnonic crystal or be blocked by tuning the strains. The result provides an advanced platform for studying the tunable skyrmion-based spin wave devices.
基金Supported by the National Basic Research Program of China under Grant No 2006CB6049, the National High-Tech Research and Development Program of China （863）, National Nature Science Foundation of China under Grant Nos 60721063, 60676057, 60731160628, 60776001 and 60820106003, the Natural Science Foundation of Jiangsu Province （BK2008019）.
文摘The complex refractive indices and the dielectric function of GaN for frequencies ranging from 0.25 to 1.22THz are obtained using THz time-domain spectroscopy. The real part of the dielectric function first decreases from 0.25 to 0.42THz and then oscillates from 0.42 to 1.22THz, whereas the imaginary part of the dielectric function is oscillating within the whole range of frequency. The simple Drude model is extended to take into account the effect of defects on the dielectric function. The extended model is in agreement with the experimental data.
基金supported by the National Natural Science Foundation of China(Grant No.61574079).
文摘We investigate the current-driven characteristics and applications of magnetic skyrmion strings by micromagnetic simulations.Under the spin-polarized driving current,the skyrmion string presents different moving trajectories in different layers due to the skyrmion Hall effect.Moreover,a series of skyrmion bobbers can be generated with a notch defect placed in the surface and the skyrmion bobbers will follow the skyrmion string.By varying the current density,the bobbers'characteristics such as number and velocity can be manipulated,which inspires us to propose a skyrmion string-based diode.In addition,an AND logic gate and an OR logic gate in the identical scheme based on the skyrmion string are proposed.AND logic and OR logic behaviors can be realized by varying the driving current densities.Our findings will contribute to further research of magnetic skyrmion strings for data storage,processing,and energy-efficient computing.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11704197 and 61574079the NUPTSF under Grant No.NY217046。
文摘A spintronic theory is developed to study the effect of lattice distortion on the magnetic tunnel junctions(MTJs)consisting of single-crystal barrier and half-metallic electrodes.In the theory,the lattice distortion is described by strain,defect concentration and recovery temperature.All three parameters will modify the periodic scattering potential,and further alter the tunneling magnetoresistance(TMR).The theoretical results show that:(1)the TMR oscillates with all the three parameters;(2)the strain can change the TMR about 30%;(3)the defect concentration will strongly modify the periodic scattering potential,and further change the TMR about 50%;and(4)the recovery temperature has little effect on the periodic scattering potential,and only can change the TMR about 10%.The present work may provide a theoretical foundation to the application of lattice distortion for MTJs consisting of single-crystal barrier and half-metallic electrodes.
