Monte Carlo Study Of Physical Properties Of Materials With Kagome Structure

Kagome lattice is a two-dimensional hexagonal network composed of shared corner triangles.Its structure has been widely concerned by the scientific community since its establishment because of its unique properties.Based on Monte Carlo simulation method,we studied the effects of different physical parameters on the dynamic phase transformation and magnetothermal effect of Kagome lattice.Firstly,for the single-layer Kagome lattice,different exchange coupling effect,the magnetocrystalline anisotropy,dynamic magnetic field on the dynamic phase transition of the ferromagnetic system are analyzed,and the results show that with the increase of|J|and|Js|,the blocking temperature of the system increases.As|D|and|D₁|increase,saturation values of dynamic order parameter change and the blocking temperature of the system decrease.In the process,the compensation behavior is observed;|h_bias|and|h_osc|obstacle to the influence of the blocking temperature of the opposite.The dynamic internal energy curves present a similar trend with the change of related parameters:they all increase slowly with the increase of temperature,and an inflection point occurs around the blocking temperature.In the mixed-spin ferromagnetic system,we analyzed effects when the|h_bias|and the exchange couplings transform,the magnetic entropy change and the relative cooling efficiency.Secondly,the dynamic magnetic phase transition of the double-layer Kagome lattice is studied.Found in the change of exchange coupling|J|,|Js|,|J₂|,the saturation values of dynamic order parameter values are not changed,and linked to the values of dynamic order parameter of the sublattices.Blocking temperature increases with the ferromagnetic exchange coupling namely system|J|and|Js|and ferromagnetic exchange coupling|J₂|increase and decreases as the crystal field anisotropic|D|and|D₁|increase.Under the specific parameters,the situation of the magnetic susceptibility curve appears double peaks and compensation behavior are observed.The internal energy increases with the increase of temperature,and the saturation values of the curve are related to the influence of the parameter values.|h_bias|and|h_osc|opposite effect on the blocking temperature,on the other hand,the angular frequency of oscillating field will have little impact on the internal energy.In the mixed-spin ferromagnetic system,the effects of various parameters on the system magnetic moment,magnetic entropy change of the system and the relative cooling power are given.It is found that the strong exchange coupling is unfavorable for the magnetic cooling efficiency of materials,and the strong bias field will increase the relative cooling power of the system.In this thesis,the phase diagrams of hindering temperature and compensating temperature are given and discussed.It is found that increasing the anisotropy of lattice with larger spin is easy to promote the appearance of compensating phenomenon.