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>Signatures of the electronic nature of pairing in high-Tc superconductors obtained by non-equilibrium boson spectroscopy
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Signatures of the electronic nature of pairing in high-Tc superconductors obtained by non-equilibrium boson spectroscopy
Understanding the pairing mechanism that gives rise to high-temperature superconductivity is one of the longest-standing problems of condensed-matter physics. Almost three decades after its discovery, even the question of whether or not phonons are involved remains a point of contention to some. Here we describe a technique for determining the spectra of bosons generated during the formation of Cooper pairs on recombination of hot electrons as they tunnel between the layers of a cuprate superconductor. The results obtained indicate that the bosons that mediate pairing decay over micrometre-scale distances and picosecond timescales, implying that they propagate at a speed of around 106 m s−1. This value is more than two orders of magnitude greater than the phonon propagation speed but close to Fermi velocity for electrons, suggesting that the pairing mechanism is mediated by unconventional repulsive electron–electron, rather than attractive electron–phonon, interactions.
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机译:了解引起高温超导的配对机制是凝聚态物理学中历史最悠久的问题之一。在被发现后将近三十年,甚至是否涉及声子的问题仍然是一些争论的焦点。在这里,我们描述了一种技术,该技术用于确定在库珀对形成时在热电子重组时在铜酸盐超导体层之间隧穿时产生的库珀对的光谱。所得结果表明介导配对的玻色子在微米级距离和皮秒时间标度上衰减,这意味着它们以约10 6 sup> m s -1 sup>的速度传播。该值比声子的传播速度大两个数量级以上,但与电子的费米速度接近,这表明配对机理是由非常规的排斥性电子-电子相互作用,而不是有吸引力的电子-声子相互作用引起的。
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