二维金属中具有一对热点的$\bf 2k_F$密度波序起始时的涨落效应
Fluctuation effects at the onset of $\bf 2k_F$ density wave order with one pair of hot spots in two-dimensional metals
摘要：
我们分析了二维金属中电荷或自旋密度波序开始时的量子涨落效应，其中无公度$2k_F$波矢连接费米表面上的一对热点。我们计算了涨落展开（单圈）中热点附近费米子自能对首阶的动量和频率依赖性。得到了具有反常频率标度和准粒子重量为零的非费米液体行为。动量依赖性产生费米速度的发散重整化和热点附近的费米表面的平坦化。超越领先的顺序计算，我们发现，一个循环的结果是不自洽的。我们发现，任何动量无关的自能与非费米液体频率指数抹去了极化函数的峰值在$2k_F$波矢量，从而破坏了有利于$2k_F$密度波的机制，而不是那些与通用波矢量。然而，一个$2k_F$密度波量子临界点可能存在于一个足够平坦的重整化费米面。
英文摘要：
We analyze quantum fluctuation effects at the onset of charge or spin density wave order in two-dimensional metals with an incommensurate $2k_F$ wave vector connecting a single pair of hot spots on the Fermi surface. We compute the momentum and frequency dependence of the fermion self-energy near the hot spots to leading order in a fluctuation expansion (one loop). Non-Fermi liquid behavior with anomalous frequency scaling and a vanishing quasi particle weight is obtained. The momentum dependence yields a divergent renormalization of the Fermi velocity and a flattening of the Fermi surface near the hot spots. Going beyond the leading order calculation we find that the one-loop result is not self-consistent. We show that any momentum-independent self-energy with a non-Fermi liquid frequency exponent wipes out the peak of the polarization function at the $2k_F$ wave vector, and thus destroys the mechanism favoring $2k_F$ density waves over those with generic wave vectors. However, a $2k_F$ density wave quantum critical point might survive in presence of a sufficiently flat renormalized Fermi surface.
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