Different is more - Selected works in heterostructures of transition metal dichalcogenides

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School of Science | Doctoral thesis (article-based) | Defence date: 2025-02-28
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Authors

Date

2025

Department

Teknillisen fysiikan laitos
Department of Applied Physics

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Mcode

Degree programme

Language

en

Pages

108 + app. 48

Series

Aalto University publication series Doctoral Theses, 22/2025

Abstract

Heterostructures are composite materials composed of different parts put together, and they are designed to bring artificial properties. Especially after the discovery of graphene in 2004 and later other two-dimensional layered materials, the idea of assembling heterostructures like toy bricks came true and became a daily routine in quantum material research. These studies continue as many heterostructures are waiting to be realized and direct synthesis and transfer technology are expecting optimization and upgrading. On the other hand, people can now expect to use simple materials and easy protocols to reproduce strongly correlated quantum phenomena shown before in complex compounds with multiple components, such as unconventional high-temperature superconductivity in cuprates, heavy fermions and quantum criticality in rare earth compounds. The simple material platform saves energy for reproducing and reduces the difficulty of analysis. The work here chooses transition metal dichalcogenides with a layered structure as the building blocks. Together with heterostructure technology, they bring new opportunities and new insights to these challenges. This booklet tries to answer the question of what more physics will emerge when assembling different materials together, by presenting several examples, as well as necessary experimental and theoretical tools. It first briefly introduces all necessary tools, e.g., the materials transition metal dichalcogenides, molecular beam epitaxy, scanning tunneling microscopy and spectroscopy tech, as well as theories such as the Hubbard model, the single impurity Anderson model and the Kondo model. Together with these techs in the odyssey of searching new quantum phases, some key findings are reported, e.g., a doped Mott insulator in the vertical heterostructure 1T/1H-NbSe2, where the 1T-phase gives Hubbard model physics and that 1H-phase acts as a charge transfer dopant; 1D interfaces in 2D lateral heterostructures 1T-VSe2—1H-NbSe2, with side-coupled Kondo resonance where VSe2 provides localized magnetic moments and NbSe2 provides conduction electrons; and finally other heterostructure applications. These compositions of different components effectively and seamlessly bring new properties which cannot be found in solo materials. These experiments successfully explore new synthesizing methods and discover new condensed matter platforms for many-body physics. These different materials, different Hamiltonian terms bring more phases and more physics.

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Supervising professor

Foster, Adam, Prof., Aalto University, Department of Applied Physics, Finland

Thesis advisor

González-Herrero, Héctor, Dr., Universidad Autónoma de Madrid, Spain
Sainio, Jani, Dr., Aalto University, Department of Applied Physics, Finland

Keywords

heterostructures, transition metal dichalcogenides, scanning tunneling microscopy

Other note

Parts

  • [Publication 1]: Xin Huang, Héctor González-Herrero, Orlando J. Silveira, Shawulienu Kezilebieke, Peter Liljeroth, Jani Sainio. Atomically sharp 1D interfaces in 2D lateral heterostructures of VSe2—NbSe2 monolayers. ACS Nano, 18, 45, 31300–31308, November 2024.
    Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202411217427
    DOI: 10.1021/acsnano.4c10302 View at publisher
  • [Publication 2]: Xin Huang, Jose L. Lado, Jani Sainio, Peter Liljeroth, Somesh C. Ganguli. Doped Mott phase and charge correlations in monolayer 1T-NbSe2. arXiv, Accepted for publication in Physical Review Letters, March 2024.
    Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202502052361
    DOI: 10.1103/PhysRevLett.134.046504 View at publisher
  • [Publication 3]: Markus Aapro, Md Nurul Huda, Jeyakumar Karthikeyan, Shawulienu Kezilebieke, Somesh C., Héctor González-Herrero, Xin Huang, Peter Liljeroth, Hannu-Pekka Komsa. Synthesis and properties of monolayer MnSe with unusual atomic structure and antiferromagnetic ordering. ACS Nano, 15, 8, 13794–13802, July 2021.
    Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202108048164
    DOI: 10.1021/acsnano.1c05532 View at publisher
  • [Publication 4]: Yaning Wang, Wanying Li, Yimeng Guo, Xin Huang, Zhaoping Luo, Shuhao Wu, Hai Wang, Jiezhi Chen, Xiuyan Li, Xuepeng Zhan, Hanwen Wang. A gate-tunable artificial synapse based on vertically assembled van der Waals ferroelectric heterojunction. Journal of Materials Science & Technology, 128, 20, 239-244, May 2022.
    DOI: 10.1016/j.jmst.2022.04.021 View at publisher

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Permanent link to this item

https://urn.fi/URN:ISBN:978-952-64-2382-1

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[diss] Perustieteiden korkeakoulu / SCI