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arXiv 1002.3823cond-mat.str-elcond-mat.supr-conhep-th
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反铁磁体和铜氧化物超导体的量子相变

Quantum phase transitions of antiferromagnets and the cuprate superconductors

Subir Sachdev

摘要:

我首先提出的全球相图的铜酸盐超导体作为载流子浓度的函数,磁场,和温度,并强调其连接到许多最近的实验。相图,然后作为出发点的各种量子相位和绝缘体,超导体和金属的相变的教学审查。用键算符方法描述了二聚反铁磁绝缘体在磁有序态和自旋能隙态之间的转变。本文将Schwinger玻色子方法应用于受抑正方晶格反铁磁体,给出了含有共线和双有序磁态、Z_2自旋液体和价键固体的相图,并用自旋子的有效规范理论描述。从这些绝缘体理论的见解,然后应用到各种对称性破缺过渡的d波超导体。后者系统也包含费米子准粒子与无质量狄拉克谱,和它们的影响的序参量波动和量子临界性进行了仔细讨论。最后,我介绍了强耦合问题与对称性破缺过渡的二维金属,其中的序参量波动耦合到一个无隙线的费米激发沿费米面。

英文摘要:

I begin with a proposed global phase diagram of the cuprate superconductors as a function of carrier concentration, magnetic field, and temperature, and highlight its connection to numerous recent experiments. The phase diagram is then used as a point of departure for a pedagogical review of various quantum phases and phase transitions of insulators, superconductors, and metals. The bond operator method is used to describe the transition of dimerized antiferromagnetic insulators between magnetically ordered states and spin-gap states. The Schwinger boson method is applied to frustrated square lattice antiferromagnets: phase diagrams containing collinear and spirally ordered magnetic states, Z_2 spin liquids, and valence bond solids are presented, and described by an effective gauge theory of spinons. Insights from these theories of insulators are then applied to a variety of symmetry breaking transitions in d-wave superconductors. The latter systems also contain fermionic quasiparticles with a massless Dirac spectrum, and their influence on the order parameter fluctuations and quantum criticality is carefully discussed. I conclude with an introduction to strong coupling problems associated with symmetry breaking transitions in two-dimensional metals, where the order parameter fluctuations couple to a gapless line of fermionic excitations along the Fermi surface.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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