论文标题
库珀的方法在基于洛杉矶的库酸酯超导体的紧密结合模型中配对地层
Cooper approach to pair formation in a tight-binding model of La-based cuprate superconductors
论文作者
论文摘要
我们以1956年的库珀方法的框架进行数值研究，在基于LA的库酸酯超导体模型中，成对形成的机制在文献中在文献中报道的较长的跳跃参数在不同的质量动量中心值中报道了。一种有效的数值方法允许研究超过一百万个站点的晶格。我们考虑有吸引力的哈伯德和D-Wave类型相互作用以及排斥的库仑相互作用的情况。基于冷冻费米海的方法导致了相对动量状态的复杂结构，该结构对静态或移动对的总成对动量非常敏感。发现与大约一半电子伏的吸引力相互作用与实验报告的关键超导温度的结果及其依赖于孔掺杂的结果具有令人满意的一致性。地基态表现出具有吸引力的哈伯德和D波相互作用的D波对称性，这实际上是由于特定的费米表面结构所致，而不是完全归因于相互作用的最终D-Wave对称性。我们还发现，在费米能量上方激发能量的库仑排斥产生的对状态，并确定其形成的不同机制。特别是，我们在相当适度的激发能的负质量区域中鉴定出这种对，这是由于特定的频带结构所致。
We study numerically, in the framework of the Cooper approach from 1956, mechanisms of pair formation in a model of La-based cuprate superconductors with longer-ranged hopping parameters reported in the literature at different values of center of mass momentum. An efficient numerical method allows to study lattices with more than a million sites. We consider the cases of attractive Hubbard and d-wave type interactions and a repulsive Coulomb interaction. The approach based on a frozen Fermi sea leads to a complex structure of accessible relative momentum states which is very sensitive to the total pair momentum of static or mobile pairs. It is found that interactions with attraction of approximately half of an electronvolt give a satisfactory agreement with experimentally reported results for the critical superconducting temperature and its dependence on hole doping. Ground states exhibit d-wave symmetries for both attractive Hubbard and d-wave interactions which is essentially due to the particular Fermi surface structure and not entirely to an eventual d-wave symmetry of the interaction. We also find pair states created by Coulomb repulsion at excited energies above the Fermi energy and determine the different mechanisms of their formation. In particular, we identify such pairs in a region of negative mass at rather modest excitation energies which is due to a particular band structure.
