Structure of the pairing interaction in the two-dimensional Hubbard model

Area of Science:

• Condensed Matter Physics
• Quantum Materials
• Superconductivity Theory

Background:

• The two-dimensional Hubbard model is a fundamental model for understanding strongly correlated electron systems, including high-temperature superconductors.
• Understanding the pairing mechanism, particularly dx2-y2 pairing, is a central challenge in condensed matter physics.

Purpose of the Study:

• To investigate the irreducible particle-particle vertex responsible for dx2-y2 pairing in the doped two-dimensional Hubbard model.
• To identify the dominant contributions to the effective pairing interaction within this model.

Main Methods:

• Dynamic cluster Monte Carlo calculations were employed to study the Hubbard model.
• An exact decomposition of the particle-particle vertex into irreducible two-fermion vertex, charge, and magnetic exchange channels was performed.

Main Results:

• The irreducible particle-particle vertex increases with momentum transfer.
• This vertex decreases when energy transfer exceeds a scale related to Q=(pi, pi) spin susceptibility.
• The magnetic, spin S=1 exchange channel was identified as the dominant contributor to the effective pairing interaction.

Conclusions:

• The magnetic exchange channel plays a critical role in mediating dx2-y2 pairing in the doped Hubbard model.
• These findings provide insights into the microscopic origins of superconductivity in related materials.