MgB₂的有效声子谱及其超导转变温度的研究

【作者】 沈龙海；

【导师】 郭振平；

【作者基本信息】 延边大学 ， 理论物理， 2003， 硕士

【摘要】 本文对二硼化镁的有效声子谱进行采样、分段、拟合，得到有效声子谱的经验谱函数。利用经验谱函数计算出电声耦合常数λ=0.81、平均声子频率〈ω〉=57.52mev、声子平方平均频率〈ω〉=3628.23mev~2=488215K~2。并基于二硼化镁材料的晶体结构，计算了库仑赝势μ~*=0.1。最后分别用Matsubara表象、线性Eliasheberg方程、Allen-Dynes、McMillan的T_c公式详细地讨论了超导转变温度，结果表明Matsubara表象下的T_c公式取N=6(七阶行列式)时的超导转变温度为37.92K，与实验值T_c=39K符合的比较好。更多还原

【Abstract】 In this paper,for the 39K-superconductor MgB₂.we attained the experiential Eliashberg function by sampling and fitting sectionally the effective phonon spec-trum of MgB₂-With the experiential Eliashberg function we calculated the electron-phonon coupling constant（EPC）A = 0.81,average phonon frequency （w）=57.52mev, square average phonon frequency (w²}=3628.23mev².Based on the crystal structure of MgB₂ ,calculated the coulomb pseudopotential of μ*=0.1. At last by contrast with the Matsubara representation .linear Eliashberg equation,Allen-Dynes,McMillan T_c expression,we analysed in detail the transition temperature T_c,which showed the result of transition temperature is up to 37.92K in Matsubara representation tak-ing N=6（7x 7 matrix） , these result is in exellent agreement with experiments T_c=39K.Our result confirm the MgB₂ is conventional phonon mechanism which can explain the observed superconductivity.更多还原