Hole crystallization in the spin ladder of Sr14Cu24O41

TL;DR

This paper provides experimental evidence for a hole crystal phase in a doped spin ladder compound, supporting theories that link charge order to high-temperature superconductivity in copper-oxide materials.

Contribution

The study confirms the existence of a hole crystal in Sr14Cu24O41 using resonant x-ray scattering, aligning with theoretical predictions and highlighting many-body effects without lattice distortion.

Findings

Evidence of a hole crystal phase in Sr14Cu24O41

Hole crystal exists without detectable lattice distortion

Supports the theory linking charge order to superconductivity

Abstract

One of the deepest questions in condensed matter physics concerns what other phases compete with superconductivity in high-transition-temperature (high-Tc) superconductors. One candidate is the "stripe" phase, in which the carriers (holes) condense into rivers of charge separating regions of antiferromagnetism. A related but lesser known system is the "spin ladder", which consists of two coupled chains of magnetic ions forming an array of rungs. A doped ladder can be thought of as a high-Tc material with lower dimensionality, and has been predicted to exhibit both superconductivity and an insulating "hole crystal" phase in which the carriers are localised through many-body interactions. The competition between the two resembles that between static stripes and superconductivity in high-Tc materials. Here we report evidence, from resonant x-ray scattering, for the existence of a hole crystal in the doped spin ladder of Sr14Cu24O41. This phase exists without a detectable distortion in the structural lattice, indicating it arises from many-body effects. Our measurements confirm theoretical predictions and support the picture that proximity to charge ordered states is a general property of superconductivity in copper-oxides.