Magnetic Properties Of Ising Nanowires And Nanotubes

In recent years,nanowires and nanotubes have potential applications in magnetic recording due to their unique physical properties.Therefore,the study of magnetic properties of nanowires and nanotubes has important academic value and application value.Ising model is the simplest physical statistical model,which can provide rich physical contents.It can not only describe the transition from order to disorder of interacting particles,but also explain the critical points and critical behavior of interacting particles in multi-body system.Therefore,it is theoretically and experimentally far-reaching significant to study the magnetic properties of materials using Ising model.The effects of physical parameters such as longitudinal magnetic field,transverse magnetic field,surface exchange interaction and interlayer exchange interaction on the magnetizations and magnetic susceptibility of the ferromagnetic and ferrimagnetic systems of cylindrical Ising nanowires and nanotubes with the longitudinal magnetic field and transverse magnetic field were investigated in detail by the use of the effective-field theory with correlations(EFT).The results show that the magnetizations of ferromagnetic and ferrimagnetic systems are quite different.The phase transition curve of the system can be approximated to a characteristic curve.It has also been found that the longitudinal magnetic field,transverse magnetic,surface exchange interaction field and interlayer exchange interaction have different effects on the longitudinal magnetizations,transverse magnetizations and susceptibility of the system.When the above physical parameters change,the effects of the surface shell and core on the total magnetizations are different.For the ferromagnetic systems of cylindrical Ising nanowires and nanotubes,the total longitudinal magnetizations decreases gradually to a constant value with the increase of temperature with specific physical parameters.The larger the longitudinal magnetic field is,the change of the total longitudinal magnetizations of the system is slower.The total transverse magnetizations of the system may decrease with the increase of the longitudinal magnetic field,surface exchange interaction and interlayer exchange interaction,and the decrease of the transverse magnetic field.The change curve of phase transition temperature with longitudinal magnetic field can be approximated to a straight line.And the phase transition temperature of the system increases with increasing of longitudinal magnetic field,surface exchange interaction and interlayer exchange interaction,and decreases with the increase of transverse magnetic field.For the ferrimagnetic systems of cylindrical Ising nanowires and nanotubes,the total longitudinal magnetizations not only has the expression form of the ferromagnetic system,but also has another form,that is,the small amplitude bulge phenomenon occurs when the total longitudinal magnetizations decreases to a small constant with the increase of temperature with specific physical parameters.When the longitudinal magnetic field,surface exchange interaction and interlayer exchange interaction are larger,and the transverse magnetic field is smaller,the change of the total longitudinal magnetizations of the system is slower.The total transverse magnetizations of the system increases with the increase of the transverse magnetic field,but the dependence on the longitudinal magnetic field,surface exchange interaction and interlayer exchange interaction is very weak.The phase transition curve of the system can be approximated to a characteristic curve.And the phase transition temperature increases with increasing of longitudinal magnetic field,surface exchange interaction and interlayer exchange interaction,and decreases with increasing of transverse magnetic field.