Considering the attractive interaction between two magnons with opposite wave vectors in a Heisenberg ferromagnet, we propose the model of magnon-pairs, which is suitable for low-temperature environment. A dressed mag...Considering the attractive interaction between two magnons with opposite wave vectors in a Heisenberg ferromagnet, we propose the model of magnon-pairs, which is suitable for low-temperature environment. A dressed magnon is an energy quantum of the magnon-pairs whose energy is a monotonically increasing function of absolute temperature. Based on the model, we re-investigate the excitation mechanism and thermodynamic properties of the Heisenberg ferromagnet. The correction factor e(0) plays an important role in studying the low-temperature properties of a ferromagnet.展开更多
We investigate asymmetric spin wave scattering behaviors caused by vortex chirality in a cross-shaped ferromagnetic system by using the micromagnetic simulations.In the system,four scattering behaviors are found:(i)as...We investigate asymmetric spin wave scattering behaviors caused by vortex chirality in a cross-shaped ferromagnetic system by using the micromagnetic simulations.In the system,four scattering behaviors are found:(i)asymmetric skew scattering,depending on the polarity of vortex core,(ii)back scattering(reflection),depending on the vortex core stiffness,(iii)side deflection scattering,depending on structural symmetry of the vortex circulation,and(iv)geometrical scattering,depending on waveguide structure.The first and second scattering behaviors are attributed to nonlinear topological magnon spin Hall effect related to magnon spin-transfer torque effect,which has value for magnonic exploration and application.展开更多
The magnetic properties of Ni/Cu multilayers, prepared by the electron beam evaporation method under ultra high vacuum conditions, have been systematically studied by magnetic measurements. The temperature dependence ...The magnetic properties of Ni/Cu multilayers, prepared by the electron beam evaporation method under ultra high vacuum conditions, have been systematically studied by magnetic measurements. The temperature dependence of the spontaneous magnetization M (T) is well described by a T3/2 law. A spin wave theory has been used to explain the magnetization versus temperature. Based on this theory, the approximate values for the exchange interactions have been obtained.展开更多
The eigenprobtems of spin waves in a symmetrical ferromagnetic bilayered system with periodic boundary conditions are solved using the interface-rescaling approach （IRA）. The results show that interface coupling bet...The eigenprobtems of spin waves in a symmetrical ferromagnetic bilayered system with periodic boundary conditions are solved using the interface-rescaling approach （IRA）. The results show that interface coupling between two sublayers would not change the excitation energy of odd bulk modes, but change excitation energy of even bulk modes. We call this peculiar phenomenon the phenomenon of even bulk mode variance （PEBMV）. There are two kinds of mechanisms which cause PEBMV： phase reversal and phase translation of the magnon at the interface, corresponding, respectively, to the antiferromagnetic and ferromagnetic interface coupling cases. PEBMV embodies the selective effect of the interface on different bulk magnons.展开更多
We study the magnon bands of twisted bilayer honeycomb quantum magnets using linear spin wave theory.Although the interlayer coupling can be ferromagnetic or antiferromagnetic,we keep the intralayer one ferromagnetic ...We study the magnon bands of twisted bilayer honeycomb quantum magnets using linear spin wave theory.Although the interlayer coupling can be ferromagnetic or antiferromagnetic,we keep the intralayer one ferromagnetic to avoid possible frustration.For the interlayer ferromagnetic case,we find the magnon bands have similar features with the corresponding electronic energy spectrums.Although the linear dispersions near the Dirac points are preserved in the magnon bands of twisted bilayer magnets,their slopes are reduced with the decrease of the twist angles.On the other hand,the interlayer antiferromagnetic couplings generate quite different magnon spectra.The two single-layered magnon spectra are usually decoupled due to the opposite orientations of the spins in the two layers.We also develop a low-energy continuous theory for very small twist angles,which has been verified to fit well with the exact tight-binding calculations.Our results may be experimentally observed due to the rapid progress in two-dimensional magnetic materials.展开更多
1 Introduction Since single crystal magnetic films which have multiple layers with the same magnetization such as LaYIG/GGG/LaYIG film were first made by the authors, they have been widely used in microwave delay line...1 Introduction Since single crystal magnetic films which have multiple layers with the same magnetization such as LaYIG/GGG/LaYIG film were first made by the authors, they have been widely used in microwave delay line with linear dispersion and other devices. Recently ferromagnetic resonance （FMR） and magnetostatic wave propagation characteristics of similar multi-layered film have been studied by many authors, whichris important for the multi-layered film to be used in microwave region. But until now many important characteristics of the multi-layered film have not been well understood. The direction and magnitude of uniaxial anisotropy effective field H<sub>11</sub>, the widening of FMR linewidth △H,展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos. 10174024 and 10474025
文摘Considering the attractive interaction between two magnons with opposite wave vectors in a Heisenberg ferromagnet, we propose the model of magnon-pairs, which is suitable for low-temperature environment. A dressed magnon is an energy quantum of the magnon-pairs whose energy is a monotonically increasing function of absolute temperature. Based on the model, we re-investigate the excitation mechanism and thermodynamic properties of the Heisenberg ferromagnet. The correction factor e(0) plays an important role in studying the low-temperature properties of a ferromagnet.
基金Project supported by the Basic Science Research Program of the National Research Foundation of Korea(Grant No.2021R1F1A1050539)the Yanbian University Research Project(Grant No.482022104)the Yichang Natural Science Research Project(Grant No.A22-3-010)。
文摘We investigate asymmetric spin wave scattering behaviors caused by vortex chirality in a cross-shaped ferromagnetic system by using the micromagnetic simulations.In the system,four scattering behaviors are found:(i)asymmetric skew scattering,depending on the polarity of vortex core,(ii)back scattering(reflection),depending on the vortex core stiffness,(iii)side deflection scattering,depending on structural symmetry of the vortex circulation,and(iv)geometrical scattering,depending on waveguide structure.The first and second scattering behaviors are attributed to nonlinear topological magnon spin Hall effect related to magnon spin-transfer torque effect,which has value for magnonic exploration and application.
文摘The magnetic properties of Ni/Cu multilayers, prepared by the electron beam evaporation method under ultra high vacuum conditions, have been systematically studied by magnetic measurements. The temperature dependence of the spontaneous magnetization M (T) is well described by a T3/2 law. A spin wave theory has been used to explain the magnetization versus temperature. Based on this theory, the approximate values for the exchange interactions have been obtained.
基金Project supported by the Foundation for Key Program of Ministry of Education,China (Grant No 206024)National Natural Science Foundation of China (Grant No 10762001)+2 种基金Program for New Century Excellent Talents in University of China (Grant NoNCET-05-0272)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No 20040126003)Natural Science Foundation of Inner Mongolia Autonomous Region,China (Grant No 200711020109)
文摘The eigenprobtems of spin waves in a symmetrical ferromagnetic bilayered system with periodic boundary conditions are solved using the interface-rescaling approach （IRA）. The results show that interface coupling between two sublayers would not change the excitation energy of odd bulk modes, but change excitation energy of even bulk modes. We call this peculiar phenomenon the phenomenon of even bulk mode variance （PEBMV）. There are two kinds of mechanisms which cause PEBMV： phase reversal and phase translation of the magnon at the interface, corresponding, respectively, to the antiferromagnetic and ferromagnetic interface coupling cases. PEBMV embodies the selective effect of the interface on different bulk magnons.
基金the National Natural Science Foundation of China(Grant Nos.11774019,11974051,and 11734002)the Fundamental Research Funds for the Central Universities and the HPC Resources at Beihang Universitythe National Key Research and Development Program of China(Grant No.2016YFA0300304)。
文摘We study the magnon bands of twisted bilayer honeycomb quantum magnets using linear spin wave theory.Although the interlayer coupling can be ferromagnetic or antiferromagnetic,we keep the intralayer one ferromagnetic to avoid possible frustration.For the interlayer ferromagnetic case,we find the magnon bands have similar features with the corresponding electronic energy spectrums.Although the linear dispersions near the Dirac points are preserved in the magnon bands of twisted bilayer magnets,their slopes are reduced with the decrease of the twist angles.On the other hand,the interlayer antiferromagnetic couplings generate quite different magnon spectra.The two single-layered magnon spectra are usually decoupled due to the opposite orientations of the spins in the two layers.We also develop a low-energy continuous theory for very small twist angles,which has been verified to fit well with the exact tight-binding calculations.Our results may be experimentally observed due to the rapid progress in two-dimensional magnetic materials.
基金Project supported by the National Natural Science Foundation of China.
文摘1 Introduction Since single crystal magnetic films which have multiple layers with the same magnetization such as LaYIG/GGG/LaYIG film were first made by the authors, they have been widely used in microwave delay line with linear dispersion and other devices. Recently ferromagnetic resonance （FMR） and magnetostatic wave propagation characteristics of similar multi-layered film have been studied by many authors, whichris important for the multi-layered film to be used in microwave region. But until now many important characteristics of the multi-layered film have not been well understood. The direction and magnitude of uniaxial anisotropy effective field H<sub>11</sub>, the widening of FMR linewidth △H,
