论文标题
电子的光谱函数耦合到硬核玻色子
Spectral Function of an Electron Coupled to Hard Core Bosons
论文作者
论文摘要
北极子是一种戴着HCB激发的电子，即使在强耦合极限处，由于其有效质量保留了自由电子质量的有效质量。该结果与荷斯坦模型形成鲜明对比，在该模型中，电子有效质量与电子偶联呈指数增长。 HCB的自由度介导了两个在任何非零耦合强度下形成绑定的单线双子状态的两个电子之间的有吸引力的电位。在电子光谱函数的低频状态下，我们观察到仅在布里鲁因区中央部分与状态的连续体分离的准颗粒（QP）条带。随着QP频段进入有限寿命的连续体，准重量的重量接近零。在有限温度下，电子可以歼灭热激发的HCB。这种热激活的过程导致QP频段下方的光谱重量的积累。虽然研究的模型与荷斯坦模型有相似之处，但我们指出了许多源自二进制HCB激发频谱的重要差异，而二进制HCB激发光谱又模仿自由度超过2美元的自由度。
The polaron, an electron dressed with HCB excitations, remains light even in the strong coupling limit as its effective mass remains of the order of the free electron mass. This result is in a sharp contrast to the Holstein model where the electron effective mass increases exponentially with the electron-phonon coupling. HCB degrees of freedom mediate the attractive potential between two electrons that form a bound singlet bipolaron state at any non-zero coupling strength. In the low-frequency regime of the electron spectral function we observe a quasi-particle (QP) band that is separated from the continuum of states only in the central part of the Brillouin zone. The quasiparticle weight approaches zero as the QP band enters the continuum where it obtains a finite lifetime. At finite temperature an electron can annihilate thermally excited HCB's. Such thermally activated processes lead to a buildup of the spectral weight below the QP band. While the investigated model bears a resemblance with the Holstein model, we point out many important differences that originate from the binary HCB excitation spectrum, which in turn mimics spin-$1\over 2$ degrees of freedom
