Reversible Structural Transition of Two-Dimensional Copper Selenide on Cu(111)

Bin Liu; Chaoqiang Xu; Xudong Xiao; Yande Que; Yuan Zhuang

arxiv: 2110.00714 · v1 · submitted 2021-10-02 · ❄️ cond-mat.mtrl-sci · cond-mat.mes-hall

Reversible Structural Transition of Two-Dimensional Copper Selenide on Cu(111)

Yuan Zhuang , Yande Que , Chaoqiang Xu , Bin Liu , Xudong Xiao This is my paper

Pith reviewed 2026-05-24 13:06 UTC · model grok-4.3

classification ❄️ cond-mat.mtrl-sci cond-mat.mes-hall

keywords CuSeCu(111)structural transitionhoneycombmoiréSTMAES2D materials

0 comments

The pith

Copper selenide on copper switches reversibly between two honeycomb structures via selenium coverage and temperature.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper demonstrates a reversible transition in two-dimensional copper selenide layers grown on a copper surface. Starting from a striped moiré pattern after initial selenization, adding more selenium and annealing produces a structure with triangular holes. Heating to higher temperatures reverses the change back to the striped form. Measurements show that the amount of selenium present controls which structure forms. This matters because it reveals a way to adjust the atomic arrangement in 2D materials using straightforward deposition and heating steps.

Core claim

Direct selenization of Cu(111) forms honeycomb CuSe monolayers featuring 1D moiré structures due to asymmetric lattice distortions from mismatch. Additional selenium deposition followed by annealing creates honeycomb CuSe with quasi-ordered triangular holes. Annealing the holed structure at higher temperature reverts it to the moiré form. Auger electron spectroscopy links these changes to variations in selenium content, establishing that both coverage and temperature govern the reversible transition.

What carries the argument

The reversible structural transition between stripe-CuSe with 1D moiré patterns and hole-CuSe with triangular hole arrays, driven by Se coverage and annealing temperature.

If this is right

Changes in Se content directly cause the switch between the two structures.
The transition can be controlled by adjusting deposition amounts and annealing conditions.
This approach offers a route to engineer different 2D configurations in the same material system.
Understanding such transitions aids in predicting behavior of similar 2D layers on metal substrates.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

Such reversible changes might enable temperature or coverage-based switching in nanoscale devices.
The mechanism could extend to other transition metal selenides where lattice mismatch plays a role.
Further studies might explore how these structural shifts affect electronic or catalytic properties.

Load-bearing premise

The STM images accurately represent the honeycomb CuSe with the specified moiré stripes or triangular holes, and the AES intensity shifts precisely measure the selenium content that triggers the structural change.

What would settle it

If controlled experiments show the structural switch occurring without corresponding changes in the AES selenium signal, or if the patterns do not match the expected honeycomb lattice upon higher resolution imaging.

Figures

Figures reproduced from arXiv: 2110.00714 by Bin Liu, Chaoqiang Xu, Xudong Xiao, Yande Que, Yuan Zhuang.

**Figure 1.** Figure 1: Formation of stripe-CuSe on Cu(111) at room temperature. (a) Atomic topographic image and (b) LEED pattern of well-ordered CuSe/Cu(111). (c) Height profiles of CuSe along the high-symmetry directions as indicated by arrows in (a). Tunneling parameters for (a) sample bias U = -0.1 V, tunneling current I = 2.5 nA. LEED pattern in (b) was taken at the energy of 90 eV [PITH_FULL_IMAGE:figures/full_fig_p005_1.png] view at source ↗

**Figure 3.** Figure 3: Reverse structural transition of CuSe on Cu(111). (a) and (b) STM topographic images after post annealing of hole-CuSe at (a) 400 ˚C and (b) 450 ˚C, respectively. (c) Atomicresolution STM topographic and (d) corresponding FFT images of the stripe structure of CuSe in (b). The white arrow in (d) denotes the reciprocal lattice vector for 1D stripe structure, whereas the yellow arrows for the hexagonal CuSe,… view at source ↗

**Figure 5.** Figure 5: Auger electron spectroscopy of CuSe/Cu(111). (a) AES spectra of CuSe with different structures. The AES peaks for Cu and Se elements are denoted by solid and dashed lines, respectively. All the spectra are normalized by the peak-peak intensity of Cu at ~110 eV. The label A-D referred to samples A-D which are defined in Figs. 2 and 3. (b) AES intensity of Se for these samples. It should be noted that the Se… view at source ↗

read the original abstract

Structural engineering opens a door to manipulating the structures and thus tuning the properties of two-dimensional materials. Here, we report a reversible structural transition in honeycomb CuSe monolayer on Cu(111) through scanning tunneling microscopy (STM) and Auger electron spectroscopy (AES). Direct selenization of Cu(111) gives rise to the formation of honeycomb CuSe monolayers with 1D moir\'e structures (stripe-CuSe), due to the asymmetric lattice distortions in CuSe induced by the lattice mismatch. Additional deposition of Se combined with post annealing results in the formation of honeycomb CuSe with quasi-ordered arrays of triangular holes (hole-CuSe), namely, the structural transition from stripe-CuSe to hole-CuSe. Further, annealing the hole-CuSe at higher temperature leads to the reverse structural transition, namely from hole-CuSe to stripe-CuSe. AES measurement unravels the Se content change in the reversible structural transition. Therefore, both the Se coverage and annealing temperature play significant roles in the reversible structural transition in CuSe on Cu(111). Our work provides insights in understanding of the structural transitions in 2D materials.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

The paper shows a reversible stripe-to-hole transition in CuSe on Cu(111) via STM, with AES suggesting Se coverage drives it, but without quantification details on the AES signal.

read the letter

The key thing to know is that this paper documents a reversible switch in a CuSe monolayer on Cu(111) from a striped 1D moiré structure to one with quasi-ordered triangular holes and back, using STM to image the changes and AES to track selenium content. They achieve the stripe form by direct selenization, then add Se and anneal to get the hole form, and use higher temperature annealing to reverse it. The STM data shows the honeycomb lattice with the respective features, and the AES signal varies with the structural changes. What the paper does well is present a clear experimental sequence demonstrating the tunability and reversibility. This adds a specific case to the body of work on structural engineering of 2D layers on metal surfaces, and the observations appear consistent with the described lattice mismatch effects. The soft spot is the AES interpretation. The claim that AES unravels the Se content change driving the transition is central, but without details on quantification, sensitivity factors, or calibration, it is difficult to confirm that the intensity changes directly correspond to monolayer coverage variations rather than other influences like beam effects or substrate interactions. This is a moderate concern for the mechanistic part of the argument. The work is for surface scientists and researchers in 2D materials on substrates. It is a standard experimental report without major internal issues, and the thinking is straightforward. I recommend sending it for peer review. The structural observation is grounded enough to warrant referee input, particularly on strengthening the composition analysis.

Referee Report

2 major / 2 minor

Summary. The manuscript reports a reversible structural transition in honeycomb CuSe monolayers on Cu(111) between stripe-CuSe (with 1D moiré structures due to lattice mismatch) and hole-CuSe (with quasi-ordered triangular holes), achieved via additional Se deposition plus annealing and reversed by higher-temperature annealing. STM images document the structural changes while AES is used to link the transitions to variations in Se content; the abstract concludes that both Se coverage and annealing temperature control the process.

Significance. If the AES intensity variations are shown to quantitatively track monolayer Se coverage, the work would demonstrate experimental control over 2D structural phases via coverage and temperature, offering a concrete example of reversible engineering in metal chalcogenides. The direct selenization approach and use of standard STM/AES are strengths for reproducibility in the field.

major comments (2)

[Abstract; AES results paragraph] Abstract and results section on AES: the claim that AES 'unravels the Se content change' responsible for the stripe-to-hole and reverse transitions lacks any reported quantification protocol. No sensitivity factors, peak-to-peak ratios, escape-depth corrections, or calibration against known coverages are provided, leaving open whether substrate diffusion, beam effects, or matrix corrections could produce the observed intensity shifts independently of surface Se atoms.
[STM results] STM interpretation section: the assignment of the observed features to honeycomb CuSe monolayers (stripe vs. hole phases) is presented without explicit comparison to simulated STM images or lattice-constant measurements that would confirm the 1D moiré periodicity and triangular-hole registry with the Cu(111) substrate.

minor comments (2)

[Figure captions] Figure captions should explicitly state the annealing temperatures, Se deposition amounts, and bias voltages used for each STM image to allow direct comparison across panels.
[Methods] The manuscript would benefit from a brief methods paragraph detailing the AES acquisition parameters (beam energy, modulation voltage) even if standard.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful reading of our manuscript and the constructive comments. We address each major comment below and will revise the manuscript to improve clarity and rigor.

read point-by-point responses

Referee: [Abstract; AES results paragraph] Abstract and results section on AES: the claim that AES 'unravels the Se content change' responsible for the stripe-to-hole and reverse transitions lacks any reported quantification protocol. No sensitivity factors, peak-to-peak ratios, escape-depth corrections, or calibration against known coverages are provided, leaving open whether substrate diffusion, beam effects, or matrix corrections could produce the observed intensity shifts independently of surface Se atoms.

Authors: We agree that the AES section lacks a detailed quantification protocol. The AES intensities are used to show relative changes in Se signal that correlate with the observed reversible structural transitions upon Se deposition and annealing. In the revised manuscript we will add the experimental AES parameters, specify that peak-to-peak heights are measured for the Se LMM and Cu LMM transitions, and clarify that the data demonstrate relative Se content variation rather than absolute calibrated coverages. We will also note that the reversibility of the transition upon annealing (without additional Se) argues against permanent beam-induced effects. The abstract will be updated to reflect this more cautious wording. revision: yes
Referee: [STM results] STM interpretation section: the assignment of the observed features to honeycomb CuSe monolayers (stripe vs. hole phases) is presented without explicit comparison to simulated STM images or lattice-constant measurements that would confirm the 1D moiré periodicity and triangular-hole registry with the Cu(111) substrate.

Authors: The high-resolution STM images in the manuscript resolve the honeycomb lattice within both phases, and the 1D moiré periodicity of the stripe phase is directly visible. In the revision we will explicitly report the measured lattice constants extracted from the STM images for both the stripe and hole phases and compare them to the known Cu(111) lattice and the expected CuSe structure. Simulated STM images are not part of the present experimental study; we will add a brief discussion of the structural registry based on the observed periodicities and cite relevant prior theoretical work on CuSe monolayers where appropriate. revision: partial

Circularity Check

0 steps flagged

No circularity: purely experimental observations

full rationale

The paper reports direct STM imaging of structural phases in CuSe monolayers on Cu(111) and AES intensity changes correlated with annealing and Se deposition. No equations, models, fitted parameters, or derivations appear in the provided text. Claims rest on observational correlation rather than any reduction of a 'prediction' to its own inputs. No self-citations, uniqueness theorems, or ansatzes are invoked. The work is self-contained against external benchmarks as standard surface-science reporting.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The claim rests on standard domain assumptions about STM contrast interpretation and AES quantification for surface Se; no free parameters, new entities, or ad-hoc axioms are introduced.

axioms (1)

domain assumption STM images can be directly interpreted as atomic honeycomb lattices with moiré or hole features
Identification of stripe-CuSe and hole-CuSe structures depends on established STM contrast rules for 2D chalcogenides on metals.

pith-pipeline@v0.9.0 · 5742 in / 1147 out tokens · 23694 ms · 2026-05-24T13:06:18.542005+00:00 · methodology

discussion (0)

Reference graph

Works this paper leans on

5 extracted references · 5 canonical work pages

[1]

Structural Engineering of 2D Nanomaterials for Energy Storage and Catalysis

(1) Zhu, Y.; Peng, L.; Fang, Z.; Yan, C.; Zhang, X.; Yu, G. Structural Engineering of 2D Nanomaterials for Energy Storage and Catalysis. Adv. Mater. 2018, 30, 1706347. (2) Zhang, B.; Sun, J. -Y.; Ruan, M. -Y.; Gao, P. -X. Tailoring Two -Dimensional Nanomaterials by Structural Engineering for Chemical and Biological Sensing. Sensors and Actuators Reports 2...

work page 2018
[2]

S.; Geim, A

(10) Novoselov, K. S.; Geim, A. K.; Morozov, S. V.; Jiang, D.; Zhang, Y.; Dubonos, S. V.; Grigorieva, I. V.; Firsov, A. A. Electric Field Effect in Atomically Thin Carbon Films. Science 2004, 306, 666–669. (11) Yuan, N. F. Q.; Mak, K. F.; Law, K. T. Possible Topological Superconducting Phases of MoS2. Phys. Rev. Lett. 2014, 113, 097001. (12) Lu, J. M.; Zh...

work page 2004
[3]

(13) Xi, X.; Wang, Z.; Zhao, W.; Park, J

Science 2015, 350, 1353–1357. (13) Xi, X.; Wang, Z.; Zhao, W.; Park, J. H.; Law, K. T.; Berger, H.; Forró , L.; Shan, J.; Mak, K. F. Ising Pairing in Superconducting NbSe2 Atomic Layers. Nat. Phys. 2016, 12, 139–

work page 2015
[4]

T.; Lee, P

(14) Law, K. T.; Lee, P. A. 1T-TaS2 as a Quantum Spin Liquid. Proc. Natl. Acad. Sci. U. S. A. 2017, 114, 6996–7000. (15) Gao, M. -R.; Xu, Y. -F.; Jia ng, J.; Yu, S. -H. Nanostructured Metal Chalcogenides: Synthesis, Modification, and Applications in Energy Conversion and Storage Devices. Chem. Soc. Rev. 2013, 42,

work page 2017
[5]

S.; Eda, G.; Li, L

(16) Chhowalla, M.; Shin, H. S.; Eda, G.; Li, L. -J.; Loh, K. P.; Zhang, H. The Chemistry of Two-Dimensional Layered Transition Metal Dichalcogenide Nanosheets. Nat. Chem. 2013, 5, 263–275. (17) Yin, Z.; Li, H.; Li, H.; Jiang, L.; Shi, Y.; Sun, Y.; Lu, G.; Zhang, Q.; Chen, X.; Zhang, H. Single-Layer MoS2 Phototransistors. ACS Nano 2012, 6, 74–80. (18) Lee...

work page 2013

[1] [1]

Structural Engineering of 2D Nanomaterials for Energy Storage and Catalysis

(1) Zhu, Y.; Peng, L.; Fang, Z.; Yan, C.; Zhang, X.; Yu, G. Structural Engineering of 2D Nanomaterials for Energy Storage and Catalysis. Adv. Mater. 2018, 30, 1706347. (2) Zhang, B.; Sun, J. -Y.; Ruan, M. -Y.; Gao, P. -X. Tailoring Two -Dimensional Nanomaterials by Structural Engineering for Chemical and Biological Sensing. Sensors and Actuators Reports 2...

work page 2018

[2] [2]

S.; Geim, A

(10) Novoselov, K. S.; Geim, A. K.; Morozov, S. V.; Jiang, D.; Zhang, Y.; Dubonos, S. V.; Grigorieva, I. V.; Firsov, A. A. Electric Field Effect in Atomically Thin Carbon Films. Science 2004, 306, 666–669. (11) Yuan, N. F. Q.; Mak, K. F.; Law, K. T. Possible Topological Superconducting Phases of MoS2. Phys. Rev. Lett. 2014, 113, 097001. (12) Lu, J. M.; Zh...

work page 2004

[3] [3]

(13) Xi, X.; Wang, Z.; Zhao, W.; Park, J

Science 2015, 350, 1353–1357. (13) Xi, X.; Wang, Z.; Zhao, W.; Park, J. H.; Law, K. T.; Berger, H.; Forró , L.; Shan, J.; Mak, K. F. Ising Pairing in Superconducting NbSe2 Atomic Layers. Nat. Phys. 2016, 12, 139–

work page 2015

[4] [4]

T.; Lee, P

(14) Law, K. T.; Lee, P. A. 1T-TaS2 as a Quantum Spin Liquid. Proc. Natl. Acad. Sci. U. S. A. 2017, 114, 6996–7000. (15) Gao, M. -R.; Xu, Y. -F.; Jia ng, J.; Yu, S. -H. Nanostructured Metal Chalcogenides: Synthesis, Modification, and Applications in Energy Conversion and Storage Devices. Chem. Soc. Rev. 2013, 42,

work page 2017

[5] [5]

S.; Eda, G.; Li, L

(16) Chhowalla, M.; Shin, H. S.; Eda, G.; Li, L. -J.; Loh, K. P.; Zhang, H. The Chemistry of Two-Dimensional Layered Transition Metal Dichalcogenide Nanosheets. Nat. Chem. 2013, 5, 263–275. (17) Yin, Z.; Li, H.; Li, H.; Jiang, L.; Shi, Y.; Sun, Y.; Lu, G.; Zhang, Q.; Chen, X.; Zhang, H. Single-Layer MoS2 Phototransistors. ACS Nano 2012, 6, 74–80. (18) Lee...

work page 2013