非常規(guī)超導的平均場理論
發(fā)布時間:2018-08-28 20:20
【摘要】:本論文用平均場理論研究非常規(guī)超導體的物理性質(zhì)。我們用平均場方法自洽地求解非常規(guī)超導的能隙函數(shù),并進一步算出比熱和倫敦穿透深度,以此來辨別超導中可能的配對方式。能隙函數(shù)的自洽方程是通過對平均場Hamiltonian做Bogoliubov變換得到的,我們求解該自洽方程,得到Bogoliubov準粒子的能譜。在此基礎上得到超導比熱和弱磁場時的倫敦穿透深度。通過比較低溫時比熱和穿透深度與溫度的冪次關(guān)系,就能推斷超導電子的配對方式。在論文的最后,我們用3帶Hubbard模型研究最近發(fā)現(xiàn)的一類超導體A2Cr3As3,發(fā)現(xiàn)其中f-wave的自旋三重態(tài)配對占主導。
[Abstract]:In this paper, the physical properties of unconventional superconductors are studied by means of the mean field theory. We use the mean field method to solve the energy gap function of the unconventional superconducting and further calculate the specific heat and the London penetration depth to identify the possible pairings in superconductivity. The self-consistent equation of the energy gap function is obtained by the Bogoliubov transformation of the mean field Hamiltonian. We solve the self-consistent equation and obtain the energy spectrum of the Bogoliubov quasiparticle. On this basis, the London penetration depth of superconducting specific heat and weak magnetic field is obtained. By comparing the power relationship between specific heat and penetration depth and temperature at low temperature, the matching mode of superconducting electrons can be inferred. At the end of the paper, we use the 3-band Hubbard model to study a class of recently discovered superconductors A _ 2Cr _ 3As _ 3, and find that the spin triplet pairing of f-wave is dominant.
【學位授予單位】:浙江大學
【學位級別】:碩士
【學位授予年份】:2015
【分類號】:TM26
本文編號:2210504
[Abstract]:In this paper, the physical properties of unconventional superconductors are studied by means of the mean field theory. We use the mean field method to solve the energy gap function of the unconventional superconducting and further calculate the specific heat and the London penetration depth to identify the possible pairings in superconductivity. The self-consistent equation of the energy gap function is obtained by the Bogoliubov transformation of the mean field Hamiltonian. We solve the self-consistent equation and obtain the energy spectrum of the Bogoliubov quasiparticle. On this basis, the London penetration depth of superconducting specific heat and weak magnetic field is obtained. By comparing the power relationship between specific heat and penetration depth and temperature at low temperature, the matching mode of superconducting electrons can be inferred. At the end of the paper, we use the 3-band Hubbard model to study a class of recently discovered superconductors A _ 2Cr _ 3As _ 3, and find that the spin triplet pairing of f-wave is dominant.
【學位授予單位】:浙江大學
【學位級別】:碩士
【學位授予年份】:2015
【分類號】:TM26
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