Moiré engineering of Cooper-pair density modulation states | Nature

## Summary
Article ADS CAS PubMed Google Scholar Papaj, M., Kong, L., Nadj-Perge, S. & Lee, P. Article ADS CAS PubMed Google Scholar Cao, Y. et al. Article ADS CAS PubMed PubMed Central Google Scholar Koz, C., Rößler, S., Tsirlin, A. Author information Author notes These authors contributed equally: Zihao Wang, Bing Xia, Stephen Paolini Authors and Affiliations Department of Physics, The Pennsylvania State University, University Park, PA, USA Zihao Wang, Bing Xia, Stephen Paolini, Zi-Jie Yan, Pu Xiao, Jiatao Song, Veer Gowda, Hongtao Rong & Cui-Zu Chang Department of Physics, University of Washington, Seattle, WA, USA Di Xiao & Xiaodong Xu Department of Materials Science and Engineering, University of Washington, Seattle, WA, USA Di Xiao & Xiaodong Xu Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, USA Weida Wu Department of Physics, Boston College, Chestnut Hill, MA, USA Ziqiang Wang Authors Zihao Wang View author publications Search author on: PubMed Google Scholar Bing Xia View author publications Search author on: PubMed Google Scholar Stephen Paolini View author publications Search author on: PubMed Google Scholar Zi-Jie Yan View author publications Search author on: PubMed Google Scholar Pu Xiao View author publications Search author on: PubMed Google Scholar Jiatao Song View author publications Search author on: PubMed Google Scholar Veer Gowda View author publications Search author on: PubMed Google Scholar Hongtao Rong View author publications Search author on: PubMed Google Scholar Di Xiao View author publications Search author on: PubMed Google Scholar Xiaodong Xu View author publications Search author on: PubMed Google Scholar Weida Wu View author publications Search author on: PubMed Google Scholar Ziqiang Wang View author publications Search author on: PubMed Google Scholar Cui-Zu Chang View author publications Search author on: PubMed Google Scholar Contributions C.Z.C. conceived and designed the experiment.

## Article Content
Subjects
Electronic properties and materials
Superconducting properties and materials
Surfaces, interfaces and thin films
Topological insulators
Abstract
Cooper-pair density modulation (CPDM) states are superconducting phases in which the order parameter varies periodically in real space without breaking translational symmetry
1
,
2
,
3
. Moiré superlattices in layered materials
4
,
5
,
6
,
7
,
8
,
9
,
10
,
11
,
12
,
13
,
14
,
15
,
16
,
17
,
18
have recently emerged as powerful platforms for engineering charge density with tunable lattice symmetry, offering a new route to creating and controlling CPDM states. Here we demonstrate moiré-induced CPDM states in a bilayer heterostructure formed by epitaxially stacking one quintuple layer (1QL) of topological insulator Sb
2
Te
3
on a six-unit-cell (6UC) antiferromagnetic FeTe layer. Scanning tunnelling microscopy and spectroscopy (STM/S) measurements reveal a moiré superlattice formed between the hexagonal tellurium lattice of Sb
2
Te
3
and the square tellurium lattice of FeTe, which spatially modulates the two superconducting gaps of the 1QL Sb
2
Te
3
/6UC FeTe bilayer. Our Josephson STM/S measurements provide direct real-space imaging of the CPDM states with a wavelength corresponding to the periodicity of the moiré superlattice. By substituting Sb
2
Te
3
with Bi
2
Te
3
, we achieve control over both the periodicity and magnitude of the CPDM states. Our work demonstrates an epitaxial strategy for synthesizing moiré superlattices from materials with different crystal symmetries and reveals a new mechanism for engineering CPDM states in designer bilayer heterostructures.
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Fig. 1: Moiré pattern and superconductivity in 1QL Sb
2
Te
3
/6UC FeTe bilayers.
Fig. 2: Moiré-induced CPDM states in 1QL Sb
2
Te
3
/6UC FeTe bilayers.
Fig. 3: Real-space imaging of CPDM states in 1QL Sb
2
Te
3
/6UC FeTe bilayers.
Fig. 4: Moiré engineering of CPDM states in 1QL (Bi,Sb)
2
Te
3
/6UC FeTe bilayers.
Data availability
The data that support the findings of this article are openly available at Zenodo via
https://doi.org/10.5281/zenodo.17139260
.
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## Expert Analysis

### Merits
- Superconductivity in a strong spin-exchange field.
- Roton pair density wave in a strong-coupling kagome superconductor.
- Direct measurement of quasiparticle-lifetime broadening in a strong-coupled superconductor.
- Scrutinizing the double superconducting gaps and strong coupling pairing in (Li 1−x Fe x )OHFeSe.

### Areas for Consideration
- Imaging the energy gap modulations of the cuprate pair-density-wave state.

### Implications
- Go to natureasia.com Buy this article Purchase on SpringerLink Instant access to the full article PDF. 39,95 € Prices may be subject to local taxes which are calculated during checkout Fig. 1: Moiré pattern and superconductivity in 1QL Sb 2 Te 3 /6UC FeTe bilayers.

### Expert Commentary
This article covers google, scholar, pubmed topics. Notable strengths include discussion of google. Areas of concern are also raised. Readability: Flesch-Kincaid grade 0.0. Word count: 2374.