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arXiv 1504.07620cond-mat.mes-hallcond-mat.str-el
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介观器件中的泛费米液体渡越和量子临界性

Universal Fermi liquid crossover and quantum criticality in a mesoscopic device

A. J. Keller, L. Peeters, C. P. Moca, I. Weymann, D. Mahalu, V. Umansky, G. Zaránd, D. Goldhaber-Gordon

摘要:

量子临界系统从零温度量子相变的影响中得到它们的有限温度性质。该范例对于理解非常规的高Tc超导体和重费米子化合物的非费米液体性质是必不可少的。然而,复杂材料中量子相变的微观起源经常被争论。在这里,我们证明了实验的支持下,通过数值重整化群计算,从量子临界非费米液体的行为,不同的费米液体基态在一个高度可控的量子点设备的通用交叉。我们的器件实现了非费米液体双通道近藤态,基于自旋1/2杂质交换耦合相等的两个独立的电子库。交换耦合的微小失谐导致在费米液体尺度T* 以下能量的更强耦合通道对自旋的常规屏蔽。我们提取了一个二次依赖的T* 门电压接近临界状态,并验证了强相关的非费米液体和费米液体状态之间的普遍交叉的渐近精确描述。

英文摘要:

Quantum critical systems derive their finite temperature properties from the influence of a zero temperature quantum phase transition. The paradigm is essential for understanding unconventional high-Tc superconductors and the non-Fermi liquid properties of heavy fermion compounds. However, the microscopic origins of quantum phase transitions in complex materials are often debated. Here we demonstrate experimentally, with support from numerical renormalization group calculations, a universal crossover from quantum critical non-Fermi liquid behavior to distinct Fermi liquid ground states in a highly controllable quantum dot device. Our device realizes the non-Fermi liquid two-channel Kondo state, based on a spin-1/2 impurity exchange-coupled equally to two independent electronic reservoirs. Arbitrarily small detuning of the exchange couplings results in conventional screening of the spin by the more strongly coupled channel for energies below a Fermi liquid scale T*. We extract a quadratic dependence of T* on gate voltage close to criticality and validate an asymptotically exact description of the universal crossover between strongly correlated non-Fermi liquid and Fermi liquid states.

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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