In this paper,the simultaneous resonance of a ferromagnetic thin plate in a time-varying magnetic field,having axial speed and being subjected to a periodic line load,is studied.Based on the large deflection theory of...In this paper,the simultaneous resonance of a ferromagnetic thin plate in a time-varying magnetic field,having axial speed and being subjected to a periodic line load,is studied.Based on the large deflection theory of thin plates and electromagnetic field theory,the nonlinear vibration differential equation of the plate is obtained by using the Hamilton′s principle and the Galerkin method.Then the boundary condition in which the longer opposite sides are clamped and hinged is considered.The dimensionless nonlinear differential equations are solved by using the method of multiple scales,and the analytical solution is given.In addition,the stability analysis is also carried out by using Lyapunov stability theory.Through numerical analysis,the variation curves of system resonance amplitude with frequency tuning parameter,magnetic field strength and external excitation amplitude are obtained.Different parameters that have significant effects on the response of the system,such as the thickness,the axial velocity,the magnetic field intensity,the position,and the frequency of external excitation,are considered and analyzed.The results show that the system has multiple solution regions and obvious nonlinear coupled characteristics.展开更多
Magnetite nanoparticles show promising applications in drug delivery,catalysis,and spintronics.The surface of magnetite plays an important role in these applications.Therefore,it is critical to understand the surface ...Magnetite nanoparticles show promising applications in drug delivery,catalysis,and spintronics.The surface of magnetite plays an important role in these applications.Therefore,it is critical to understand the surface structure of Fe_(3)O_(4)at atomic scale.Here,using a combination of first-principles calculations,particle swarm optimization(PSO)method and machine learning,we investigate the possible reconstruction and stability of Fe_(3)O_(4)(001)surface.The results show that besides the subsurface cation vacancy(SCV)reconstruction,an A layer with Fe vacancy(A-layer-V_(Fe))reconstruction of the(001)surface also shows very low surface energy especially at oxygen poor condition.Molecular dynamics simulation based on the iron–oxygen interaction potential function fitted by machine learning further confirms the thermodynamic stability of the A-layer-V_(Fe)reconstruction.Our results are also instructive for the study of surface reconstruction of other metal oxides.展开更多
We report the successful growth and characterization of Li_9Cr_3(P_2O_7)_3(PO_4)_2single crystal,and investigate its magnetic properties under external magnetic fields via magnetization and heat capacity measurements....We report the successful growth and characterization of Li_9Cr_3(P_2O_7)_3(PO_4)_2single crystal,and investigate its magnetic properties under external magnetic fields via magnetization and heat capacity measurements.Our study reveals that Li_9Cr_3(P_2O_7)_3(PO_4)_2 is an easy-plane kagome ferromagnet with S=3/2,as evidenced by the Curie–Weiss temperature of 6 K which implies a ferromagnetic exchange coupling in the material.Under zero magnetic field,Li_9Cr_3(P_2O_7)_3(PO_4)_2 undergoes a magnetic transition at TC=2.7 K from a paramagnetic state to a ferromagnetically ordered state with the magnetic moment lying in the kagome plane.By applying a c-axis directional magnetic field to rotate the spin alignment from the kagome plane to the c-axis,we observe a reduction in the magnetic transition temperature as the field is increased.We construct a magnetic phase diagram as a function of temperature and magnetic field applied parallel to the c-axis of Li_9Cr_3(P_2O_7)_3(PO_4)_2 and find that the phase boundary is linear over a certain temperature range.Regarding that theoretically,the field-induced phase transition of the spin reorientation in the easy-plane ferromagnet can be viewed as the ferromagnetic magnon Bose–Einstein condensation(BEC),the phase boundary scaling of field-induced(B c)magnetic transition in Li_9Cr_3(P_2O_7)_3(PO_4)_2 can be described as the quasi-2D magnon BEC,which has been observed in other ferromagnetic materials such as K_2CuF_4.展开更多
基金National Natural Science Foundation of China under Grant Nos.12172321 and 11472239Hebei Provincial Natural Science Foundation of China under Grant No.A2020203007Hebei Provincial Graduate Innovation Foundation of China under Grant No.CXZZBS2022146。
文摘In this paper,the simultaneous resonance of a ferromagnetic thin plate in a time-varying magnetic field,having axial speed and being subjected to a periodic line load,is studied.Based on the large deflection theory of thin plates and electromagnetic field theory,the nonlinear vibration differential equation of the plate is obtained by using the Hamilton′s principle and the Galerkin method.Then the boundary condition in which the longer opposite sides are clamped and hinged is considered.The dimensionless nonlinear differential equations are solved by using the method of multiple scales,and the analytical solution is given.In addition,the stability analysis is also carried out by using Lyapunov stability theory.Through numerical analysis,the variation curves of system resonance amplitude with frequency tuning parameter,magnetic field strength and external excitation amplitude are obtained.Different parameters that have significant effects on the response of the system,such as the thickness,the axial velocity,the magnetic field intensity,the position,and the frequency of external excitation,are considered and analyzed.The results show that the system has multiple solution regions and obvious nonlinear coupled characteristics.
基金the National Natural Science Foundation of China(Grant Nos.12004064,12074053,and 91961204)the Fundamental Research Funds for the Central Universities(Grant No.DUT22LK11)XingLiaoYingCai Project of Liaoning Province,China(Grant No.XLYC1907163)。
文摘Magnetite nanoparticles show promising applications in drug delivery,catalysis,and spintronics.The surface of magnetite plays an important role in these applications.Therefore,it is critical to understand the surface structure of Fe_(3)O_(4)at atomic scale.Here,using a combination of first-principles calculations,particle swarm optimization(PSO)method and machine learning,we investigate the possible reconstruction and stability of Fe_(3)O_(4)(001)surface.The results show that besides the subsurface cation vacancy(SCV)reconstruction,an A layer with Fe vacancy(A-layer-V_(Fe))reconstruction of the(001)surface also shows very low surface energy especially at oxygen poor condition.Molecular dynamics simulation based on the iron–oxygen interaction potential function fitted by machine learning further confirms the thermodynamic stability of the A-layer-V_(Fe)reconstruction.Our results are also instructive for the study of surface reconstruction of other metal oxides.
基金Shenzhen Fundamental Research Program(Grant No.JCYJ20220818100405013)。
文摘We report the successful growth and characterization of Li_9Cr_3(P_2O_7)_3(PO_4)_2single crystal,and investigate its magnetic properties under external magnetic fields via magnetization and heat capacity measurements.Our study reveals that Li_9Cr_3(P_2O_7)_3(PO_4)_2 is an easy-plane kagome ferromagnet with S=3/2,as evidenced by the Curie–Weiss temperature of 6 K which implies a ferromagnetic exchange coupling in the material.Under zero magnetic field,Li_9Cr_3(P_2O_7)_3(PO_4)_2 undergoes a magnetic transition at TC=2.7 K from a paramagnetic state to a ferromagnetically ordered state with the magnetic moment lying in the kagome plane.By applying a c-axis directional magnetic field to rotate the spin alignment from the kagome plane to the c-axis,we observe a reduction in the magnetic transition temperature as the field is increased.We construct a magnetic phase diagram as a function of temperature and magnetic field applied parallel to the c-axis of Li_9Cr_3(P_2O_7)_3(PO_4)_2 and find that the phase boundary is linear over a certain temperature range.Regarding that theoretically,the field-induced phase transition of the spin reorientation in the easy-plane ferromagnet can be viewed as the ferromagnetic magnon Bose–Einstein condensation(BEC),the phase boundary scaling of field-induced(B c)magnetic transition in Li_9Cr_3(P_2O_7)_3(PO_4)_2 can be described as the quasi-2D magnon BEC,which has been observed in other ferromagnetic materials such as K_2CuF_4.
