Compositional Evolution of the Anti-phase Stripe Superstructure in Bi2Sr2-xLaxCuO6 (0<x<=1.1) Revealed by Transmission Electron Microscopy

TL;DR

This study investigates the evolution of superstructures in La-doped Bi2Sr2-xLaxCuO6 using TEM, revealing a new anti-phase stripe superstructure and its relation to existing modulations, with implications for electronic properties.

Contribution

It uncovers a new anti-phase stripe superstructure in La-Bi2201 and elucidates its relation to known supermodulations through TEM analysis.

Findings

Identification of a new anti-phase stripe superstructure with a specific modulation vector.

Evolution of the incommensurate supermodulation from monoclinic to orthogonal with La doping.

Structural implications for electronic properties discussed via ARPES experiments.

Abstract

The detailed structural properties of La-doped Bi2Sr2-xLaxCuO6 (La-Bi2201, 0<=x<=1.1) have been studied by transmission electron microscopy (TEM). The well-known incommensurate supermodulation q1 in the Bi-based cuprates evolves from a monoclinic superstructure in the pristine Bi2201 phase to an orthogonal one in La-Bi2201(x=0.73) phase. The b-component of the modulation vector (q1) for x=0.25 sample is about 0.24b* and increases slightly to 0.246b* in x=0.84 sample, while it increases significantly to 0.286b* for x=1.10 sample. We have revealed a new anti-phase stripe superstructure in all the La-doped Bi2201 samples, giving rise to a new modulation with a vector q2. This q2 modulation is directly evolved from the orthogonal modulation q1 through an addition of the anti-phase structure so that its vector q2 equals to q1b/2. We also discussed the implication of these structural studies on the electronic structure by angle-resolved photoemission spectroscopy (ARPES) experiments in La-Bi2201.