Dopant-induced stabilization of three-dimensional charge order in cuprates

TL;DR

This study reveals how Pr doping at specific lattice sites in YBCO7 stabilizes three-dimensional charge order by inducing structural distortions that pin charge stripes, with implications for engineering electronic properties.

Contribution

It identifies Ba-site Pr substitution and lattice pinning as the key mechanisms for stabilizing 3D charge order in Pr-doped YBCO7, providing a quantitative framework for material design.

Findings

Pr doping at Ba sites induces inward lattice distortion.

Structural pinning correlates with increased charge order coherence.

Monte Carlo simulations match experimental observations of charge order.

Abstract

We investigate the microscopic mechanisms behind the stabilization of three-dimensional (3D) charge order by Pr doping in YBa$_2$Cu$_3$O$_7$ (YBCO7). Density-functional-theory calculations locate the lowest-energy Pr superlattices for both Ba- and Y-site substitution. In the Ba-site case, the smaller Pr ion pulls the surrounding atoms inward. This breathing-mode distortion pins charge-stripe walls to the Pr columns and forces them to align along the $c$ axis. Y-site Pr is larger than the host ion, produces an outward distortion, and fails to pin the stripes. Coarse-grained Monte-Carlo simulations show that the stripe correlation length rises in step with the structural correlation length of the Pr dopant as observed in prior experiments. We thus identify Ba-site substitution and dopant-induced lattice pinning as the key mechanism behind 3D charge order in Pr-doped YBCO7. This approach provides quantitative guidelines for engineering electronic orders through targeted ionic substitution.