AI 中文总结
本文通过非微扰改进的两粒子自洽方法，预测二维体系中非常规量子临界点处存在鲁棒奇异金属，其电阻率随温度线性缩放但无线性温度自能，为奇异金属行为提供了新的理论解释。
AI 中文摘要
二维哈伯德模型的性质（含最近邻跃迁）正受到冷原子实验和图示量子蒙特卡罗方法的密切研究。鉴于这些方法的可控性，对奇异金属行为及其与量子临界性质的关联进行预测恰逢其时。即使在低于莫特跃迁的相互作用强度下，在分隔费米液体与非公度自旋密度波序的量子临界点也会出现若干特殊现象。本文采用非微扰改进的两粒子自洽方法预测：当关联长度范围约为1至100个晶格间距时，基础费米面上的科恩异常会导致非常规临界指数；单粒子自能的温度依赖性沿费米面呈现强动量依赖性，无清晰的朗道准粒子证据；但仍观测到奇异金属行为，即当T→0时，电阻率随温度线性缩放。本研究表明，电阻率的线性温度依赖性可在费米面无线性温度自能的情况下产生，而这与通常假设的情况不同。
英文摘要
Properties of the two-dimensional Hubbard model with nearest-neighbor hopping are under scrutiny in cold-atom experiments and diagrammatic quantum Monte Carlo. Given the controlled nature of these approaches, it is timely to make predictions about strange-metal behavior and its relation to quantum-critical properties. Even for interaction strengths below the Mott transition, several peculiarities occur at the quantum critical point separating Fermi liquid and incommensurate spin-density wave order. Here, we predict, using the non-perturbative improved two-particle self-consistent approach, that for correlation lengths ranging from about one to one hundred lattice spacings, Kohn anomalies on the underlying Fermi surface lead to unconventional critical exponents. The temperature dependence of the single-particle self-energy acquires strong momentum dependence along the Fermi surface with no clear evidence of Landau quasiparticles. Nevertheless, we observe strange-metal behavior, namely, resistivity that scales linearly with temperature as $T\rightarrow{0}$. Our work shows that a linear temperature dependence of resistivity arises without a linear-in-temperature self-energy along the Fermi surface, as is often assumed.
Comments9 pages, 5 figures
