弱阻尼玻色子与反铁磁金属转变附近的先驱能隙
Weakly damped bosons and precursor gap in the vicinity of an antiferromagnetic metallic transition
AI总结：
本文研究反铁磁量子临界点附近金属的电子谱函数，发现热点处存在先驱能隙特征，但所需参数比可能不适用于实验，且低频下谱函数呈ω^{-1/2}奇异性，并通过蒙特卡罗模拟验证。
摘要：
我们研究了金属在反铁磁（AFM）量子临界点附近的电子谱函数，重点关注自旋涨落的裸带宽显著小于费米能量的情况。在此极限下，我们确定了一个能量范围，其中费米面上“热点”附近的费米准粒子被量子临界涨落强烈散射，而电子对AFM涨落的阻尼可以忽略不计。在一圈近似下，存在一个参数范围，其中热点处的$T=0$谱函数具有“先驱能隙”特征，即在有限频率处出现局部最大值。然而，获得先驱能隙所需的裸自旋波速度与费米速度之比可能太小，无法解释电子掺杂铜氧化物超导体中的实验（He等人，Proc. Natl. Acad. Sci 116, 3449 (2019)）。在较低频率下，AFM涨落的朗道阻尼变得重要，电子谱函数具有熟悉的$ω^{-1/2}$奇异性。我们的一圈微扰结果得到了电子耦合到无阻尼、近临界AFM模式的数值蒙特卡罗模拟的支持。
英文摘要：
We study the electronic spectral function of a metal in the vicinity of an antiferromagnetic (AFM) quantum critical point, focusing on a situation where the bare bandwidth of the spin fluctuations is significantly smaller than the Fermi energy. In this limit, we identify a range of energies where the fermionic quasiparticles near the "hot spots'' on the Fermi surface are strongly scattered by the quantum critical fluctuations, whereas the damping of the AFM fluctuations by the electrons is negligible. Within a one-loop approximation, there is a parameter range where the $T=0$ spectral function at the hot spots has a "precursor gap'' feature, with a local maximum at a finite frequency. However, the ratio of the bare spin wave velocity to the Fermi velocity required to obtain a precursor gap is probably too small to explain experiments in the electron-doped cuprate superconductors (He et al., Proc. Natl. Acad. Sci 116, 3449 (2019)). At lower frequencies, the Landau damping of the AFM fluctuations becomes important, and the electronic spectral function has the familiar $ω^{-1/2}$ singularity. Our one-loop perturbative results are supported by a numerical Monte Carlo simulation of electrons coupled to an undamped, nearly-critical AFM mode.
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