Exact theory for superconductivity in a doped Mott insulator
Exact theory for superconductivity in a doped Mott insulator
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DOI：
10.1038/s41567-020-0988-4
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发表时间：
2020-07-27
期刊：
影响因子：
19.6
通讯作者：
Huang, Edwin W.
中科院分区：
文献类型：
--
作者：
Phillips, Philip W.;Yeo, Luke;Huang, Edwin W.
因为铜氧化物超导体是掺杂的莫特绝缘体，所以即使是一个玩具模型，也可以同时表现出莫特性和超导性。我们考虑Hatsugai-Kohmoto模型（1，2），一个精确可解系统，它是一个原型Mott绝缘体。无论是掺杂或降低相互作用强度，我们的精确计算表明，该系统成为一个非费米液态金属超导不稳定性。在存在弱配对相互作用的情况下，不稳定性产生到超导相的热转变，这不同于由Bardeen-Cooper-Schrieffer（BCS）理论描述的传统状态，如由超过通用BCS极限的间隙与转变温度比所证明的。这种超导体的基本激发不是Bogoliubov准粒子，而是doublons和holons的叠加，复合激发表明掺杂的Mott绝缘体的超导基态继承了正常态的非费米液体特性。这个模型的一个意想不到的特点是，它表现出超导诱导的光谱权重从高能量到低能量的转移，如在铜氧化物（3）中所看到的，以及相对于BCS理论的超流密度的抑制。莫特绝缘体基态是高温超导体（如铜氧化物）的一个重要特征。在这里，作者找到了一个包含超导性和Mottness的精确可解模型。
Because the cuprate superconductors are doped Mott insulators, it would be advantageous to solve even a toy model that exhibits both Mottness and superconductivity. We consider the Hatsugai-Kohmoto model(1,2), an exactly solvable system that is a prototypical Mott insulator. Upon either doping or reducing the interaction strength, our exact calculations show that the system becomes a non-Fermi liquid metal with a superconducting instability. In the presence of a weak pairing interaction, the instability produces a thermal transition to a superconducting phase, which is distinct from the traditional state described by Bardeen-Cooper-Schrieffer (BCS) theory, as evidenced by a gap-to-transition temperature ratio exceeding the universal BCS limit. The elementary excitations of this superconductor are not Bogoliubov quasiparticles but rather superpositions of doublons and holons, composite excitations that show that the superconducting ground state of the doped Mott insulator inherits the non-Fermi liquid character of the normal state. An unexpected feature of this model is that it exhibits a superconductivity-induced transfer of spectral weight from high to low energies, as seen in the cuprates(3), as well as a suppression of the superfluid density relative to that in BCS theory.The Mott insulator ground state is a crucial feature of high-temperature superconductors such as the cuprates. Here, the authors find an exactly solvable model that contains both superconductivity and Mottness.