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arXiv 2403.09765cond-mat.str-elcond-mat.supr-con
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Hubbard模型中高$T_c$超导性的微扰描述:通过幺正变换和经典自旋

Perturbative description of high-$T_c$ superconductivity in the Hubbard model via unitary transformation and classical spins

Kirill Alpin

AI总结:

通过幺正变换和微扰理论,将Hubbard模型映射为经典自旋系统,并发现其基态控制高$T_c$超导性的出现。

摘要:

对Hubbard模型应用幺正变换,将Hubbard相互作用映射为单粒子项。所得哈密顿量由无约束费米子组成,随后被映射为与赝自旋耦合的无自旋费米子的哈密顿量。利用$1/U$的二阶微扰理论积分掉费米子,得到有效的自旋哈密顿量。识别出一个序参量,该序参量稳定d波超导性。在临界化学势之后,经典自旋构型的基态能量在该序参量的有限值处最小化,导致在非零掺杂下出现d波超导性。这表明高$T_c$超导性的出现受经典自旋系统基态的控制。

英文摘要:

A unitary transformation is applied to the Hubbard model, which maps the Hubbard interaction to a single particle term. The resulting Hamiltonian consists of unconstrained fermions, which is then mapped to a Hamiltonian of spinless fermions coupled to pseudospins. The fermions are integrated out using second order perturbation theory in $1/U$, resulting in an effective spin Hamiltonian. An order parameter is identified, stabilizing d-wave superconductivity. The groundstate energy of classical spin configurations is minimized at a finite value of this order parameter after a critical chemical potential, resulting in d-wave superconductivity at non-zero doping. This suggests, that the onset of high-$T_c$ superconductivity is governed by the groundstate of a classical spin system.

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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