Blume-Emery-Griffiths纳米管的热力学与相变性质

Thermodynamics and phase transitions of Blume-Emery-Griffiths model on nanotube

利用有效场理论研究了柱形纳米管上Blume-Emery-Griffiths系统的热力学与相变性质,得到了系统的磁化强度、磁化率、比热和相图.讨论了四次交换作用与二次交换作用的比值r与晶格场对系统热力学量和相图的影响.研究发现:系统存在三临界点,且三临界点由参数r和晶格场共同决定,即若确定了参数r,则三临界点所对应的晶格场也能确定.随着参数r的增加,系统出现三临界点时所对应的温度和晶格场也相应增大.

We have investigated Blume-Emery-Griffiths model on a cylindrical nanotube by using the effective field theory. Magnetization, magnetic susceptibility and specific heat expressions have been found and calculated numerically for different crystal fields and different values of （ is the ratio of biquadratic exchange interaction to bilinear exchange interaction）. The figures of magnetization, magnetic susceptibility, specific heat and phase diagram have been got to describe the physics phenomenon of the system. There exist first- and second-order phase transitions in this system. And the tricritical point depends on the competition between the parameter and the crystal fields. When the value of is increased, the tricritical point of temperature is increased.