Current-current correlations in the three-band model for two-leg CuO ladders

TL;DR

This study investigates current correlations in a three-band Hubbard model for two-leg CuO ladders, revealing that while correlations suggest possible circulating current phases, they do not dominate or lead to CC order in realistic conditions.

Contribution

It provides the first detailed DMRG analysis of current correlations in the three-band model for CuO ladders, clarifying the absence of circulating current order.

Findings

Current correlations decay exponentially at low doping.

Power-law decay of correlations at higher doping.

No evidence of circulating current order in realistic parameters.

Abstract

We study current-current correlations in the three-band Hubbard model for two-leg CuO ladders using the density-matrix renormalization group method. We find that these correlations decrease exponentially with distance for low doping but as a power law for higher doping. Their pattern is compatible with the circulating current (CC) phase which Varma has proposed to explain the pseudo-gaped metallic phase in underdoped high-temperature superconductors. However, for model parameters leading to a realistic ground state in the undoped ladder, the current fluctuations decay faster than the d-wave-like pairing correlations in the doped state. Thus we conclude that no phase with CC order or dominant CC fluctuations occur in the three-band model of two-leg CuO ladders.