期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2022
卷号：119
期号：1
DOI：10.1073/pnas.2109406119
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance
The Hubbard model plays a central role in the theory of highly correlated systems. Its simplicity allows conceptual issues—which are generally complicated in the context of experiments on interesting materials—to be sharply posed and definitively answered. Recently, a variety of numerical studies have led to the conclusion that the “pure” Hubbard model on the square lattice at intermediate coupling,
U, is not superconducting in the range of electron densities in which many previous approximate treatments had inferred high-temperature superconductivity. Here, using controlled density matrix renormalization group methods, we show that superconductivity is spectacularly enhanced if the hopping matrix elements are periodically modulated in a stripe-like pattern, with important (if suggestive) implications concerning the mechanism of unconventional superconductivity.
Unidirectional (“stripe”) charge density wave order has now been established as a ubiquitous feature in the phase diagram of the cuprate high-temperature superconductors, where it generally competes with superconductivity. Nonetheless, on theoretical grounds it has been conjectured that stripe order (or other forms of “optimal” inhomogeneity) may play an essential positive role in the mechanism of high-temperature superconductivity. Here, we report density matrix renormalization group studies of the Hubbard model on long four- and six-leg cylinders, where the hopping matrix elements transverse to the long direction are periodically modulated—mimicking the effect of putative period 2 stripe order. We find that even modest amplitude modulations can enhance the long-distance superconducting correlations by many orders of magnitude and drive the system into a phase with a substantial spin gap and superconducting quasi–long-range order with a Luttinger exponent,
K
s
c
∼
1
.
