Zinc impurities in d-wave superconductors

Area of Science:

• Condensed matter physics
• Quantum magnetism
• Superconductivity

Background:

• The two-dimensional Hubbard model is a fundamental model for understanding strongly correlated electron systems.
• Nonmagnetic impurities can significantly alter the electronic and magnetic properties of superconductors.
• Understanding impurity effects is crucial for designing high-performance materials.

Purpose of the Study:

• To investigate the impact of nonmagnetic zinc (Zn) impurities on d-wave superconductivity and magnetic correlations in the two-dimensional Hubbard model.
• To determine the relationship between Zn concentration and the superconducting critical temperature (Tc).
• To analyze the behavior of spin susceptibility in the presence of Zn impurities.

Main Methods:

• Utilizing quantum Monte Carlo simulations.
• Employing the dynamical cluster approximation (DCA) for accurate calculations.
• Modeling nonmagnetic Zn impurities using binary diagonal disorder.

Main Results:

• A strong suppression of d-wave superconductivity with increasing Zn content.
• An enhancement of antiferromagnetic spin correlations as Zn concentration increases.
• Linear vanishing of the superconducting critical temperature (Tc) with Zn impurity concentration.
• A change in spin susceptibility from pseudogap to Curie-Weiss-like behavior, indicating free magnetic moments.

Conclusions:

• Zinc impurities disrupt superconductivity and induce magnetic moments in the two-dimensional Hubbard model.
• The observed phenomena are consistent with the resonating-valence-bond (RVB) picture.
• These findings provide insights into the interplay between disorder, magnetism, and superconductivity in correlated electron systems.