本文關(guān)鍵詞：重電子系統(tǒng)中的關(guān)聯(lián)效應(yīng)　出處：《蘭州大學(xué)》2016年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 重費(fèi)米子 拓?fù)浣俳^緣體 非費(fèi)米液體 d波超導(dǎo)

【摘要】：重費(fèi)米子/電子系統(tǒng)是現(xiàn)代凝聚態(tài)物理研究中最活躍的領(lǐng)域之一,在這類體系中不斷涌現(xiàn)出各類新奇的層展現(xiàn)象,例如重費(fèi)米液體行為,非常規(guī)超導(dǎo)電性,奇異金屬以及量子臨界性。但是由于傳統(tǒng)的平均場(chǎng)和微擾理論近似并不足以抓住該類系統(tǒng)中起主導(dǎo)作用的電子關(guān)聯(lián)效應(yīng)的本質(zhì),相關(guān)的理論研究進(jìn)展相對(duì)比較緩慢且沒(méi)有受到應(yīng)有的重視。然而,我們發(fā)現(xiàn)輔助粒子基于的平均場(chǎng)方法和以量子蒙特卡洛與動(dòng)力學(xué)平均場(chǎng)為代表的數(shù)值技術(shù)的發(fā)展已經(jīng)改變了重費(fèi)米子理論研究的原始狀況,因而,在這些令人欣喜的進(jìn)展鼓舞之下,我們?cè)谶@篇博士論文以常見(jiàn)的量子晶格模型如Kondo晶格以及周期性Anderson模型出發(fā),通過(guò)解析與數(shù)值計(jì)算方法系統(tǒng)化地研究重費(fèi)米子體系中的電子關(guān)聯(lián)效應(yīng)。具體而言,我們提出了重費(fèi)米子量子臨界行為的一種新的理論解釋,即軌道選擇正交金屬相變。這種基于Z2輔助自旋表示的輔助粒子形式能夠正確解釋實(shí)驗(yàn)觀測(cè)到的熱容對(duì)數(shù)發(fā)散以及電阻的準(zhǔn)線性行為。當(dāng)考慮自旋-軌道耦合效應(yīng)時(shí),六角近藤晶格模型可存在新有序態(tài),即拓?fù)渥孕芏炔☉B(tài)。這類具有非平凡電磁響應(yīng)的反鐵磁自旋密度波是超越傳統(tǒng)拓?fù)浣俳^緣體的新物態(tài)。為了進(jìn)一步理解近藤體系的拓?fù)湫再|(zhì),我們對(duì)近藤項(xiàng)鏈模型的拓?fù)湫再|(zhì)進(jìn)行了探索。在這類模型中,體系的拓?fù)湫再|(zhì)可由量子非線性sigma模型以及相應(yīng)的拓?fù)漤?xiàng)共同描述。值得注意的是,高維近藤項(xiàng)鏈模型可能支持對(duì)稱保護(hù)拓?fù)鋺B(tài)。最后,以Kondo-Heisenberg模型為例,研究了重費(fèi)米子超導(dǎo)體的費(fèi)米面結(jié)構(gòu)以及超導(dǎo)配對(duì)問(wèn)題。詳細(xì)的計(jì)算表明局域磁性交換相互作用可誘導(dǎo)d波配對(duì),超導(dǎo)態(tài)的物理可觀測(cè)量與實(shí)驗(yàn)測(cè)量定性一致。這說(shuō)明重費(fèi)米子超導(dǎo)電性的某些基本性質(zhì)可通過(guò)簡(jiǎn)單的BCS平均場(chǎng)理論得以解釋。我們希望這里的研究對(duì)于進(jìn)一步理解復(fù)雜的重費(fèi)米物理有所裨益。
[Abstract]:Heavy fermion / electronic system is one of the most active fields in modern condensed matter physics. Various novel layering phenomena have been emerging in this kind of system, such as heavy fermion liquid behavior and unconventional superconductivity. Singular metals and quantum criticality, but because of the traditional mean field and perturbation theory approximation is not enough to grasp the essence of the electronic correlation effect which plays a leading role in this kind of systems. The relative theoretical research progress is relatively slow and has not received due attention. We find that the development of the mean field method based on the auxiliary particle and the numerical technique represented by the quantum Monte Carlo and the dynamical mean field has changed the original state of the heavy fermion theory. Encouraged by these encouraging developments, we set out in this doctoral thesis with common quantum lattice models such as Kondo lattices and periodic Anderson models. The electron correlation effect in the heavy fermion system is systematically studied by analytical and numerical methods. In particular, a new theoretical explanation of the quantum critical behavior of the heavy fermion is proposed. This auxiliary particle form based on Z2-assisted spin representation can correctly explain the logarithmic divergence of heat capacity observed in the experiment and the linear behavior of the resistor. When the spin-orbit coupling is considered, the phase transition of the orthorhombic metal is selected. Effect time. A new ordered state can be found in the lattice model of hexagonal Kondo. This kind of antiferromagnetic spin density wave with nontrivial electromagnetic response is a new physical state beyond the traditional topological Kondo insulator. In order to further understand the topological properties of Kondo system. We explore the topological properties of Kondo necklaces model, in which the topological properties of the system can be described by the quantum nonlinear sigma model and the corresponding topological terms. High-dimensional Kondo necklaces model may support symmetric protection topology. Finally, take the Kondo-Heisenberg model as an example. The Fermi surface structure and superconducting pairing of heavy fermion superconductors are studied. The detailed calculation shows that local magnetic exchange interaction can induce d wave pairing. The physical observable measurements of superconducting states are qualitatively consistent with the experimental measurements. This shows that some basic properties of the superconductivity of fermions can be explained by simple BCS mean field theory. It helps to understand complex Fermi physics.
【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：O469
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本文編號(hào)：1358713