Nanoelectromechanics in van der Waals heterostructures

Lead Research Organisation: University of Manchester
Department Name: Physics and Astronomy

Abstract

One of the greatest physicists Richard Feynman more than 50 years ago explored the immense possibilities of miniaturisation and presented them concisely in his talk "Plenty of Room at the Bottom". His vision becomes reality now - thanks to the advances in nanoscience and nanotechnology. The size of electronic compounds has been reduced exponentially over the past 40 years, which has brought us to a modern, globally interconnected world of mobile devices. Furthermore, miniaturisation of electrified machinery (microelectromechanical systems) has revolutionised the field of sensors and actuators. Further miniaturisation might lead to futuristic applications such as medical and industrial nanorobots in the long term. On a shorter time scale, disruptive technologies in the fields of wearable computers, self-powered devices, and smart materials are foreseen.

Although extremely appealing for both academia and industry, further progress in nanomachinery depends on solving the significant technological challenges, such as device reliability, motion control at the nanoscale, manufacturing scalability and so on. I am convinced that 2D materials and van der Waals heterostructures will revolutionize science and technology of nanoelectromechanical systems and will help to overcome these challenges.

This fellowship aims to deepen fundamental understanding of coupling of mechanical and electronic degrees of freedom at the nanoscale, and to design and fabricate electrified nanomachines using recently discovered graphene and a new class of synthetic materials - van der Waals heterostructures - layer-by-layer assembled stacks of individual atomic planes.

Van der Waals heterostructures are the ideal candidates for the next generation of nanoelectromechanical systems because (i) their mechanical strength and the crystal quality are exceptionally good; (ii) 2D materials are atomically thin, hence they represent an ultimate limit of miniaturisation and (iii) friction in this system can be controlled, leading at the right conditions to superlubricity - frictionless and wearless motion at high speed and so on.

With this fellowship a new research field in graphene/2D materials will be started at The University of Manchester. The research will be focused on coupling mechanical response of 2D materials with electrical excitation, and vice versa. The University of Manchester currently leads graphene and other 2D materials research worldwide, but the competition in this field is growing rapidly (especially in USA and China), thus making it more challenging for UK researchers to compete later. Starting this work as soon as possible provides the unique opportunity not to be missed. Moreover, close collaboration with National Graphene Institute at The University of Manchester will strengthen this research and will help with delivering the prototype devices and technologies to forthcoming industrial partners.

Planned Impact

Academic Impact:
Understanding the interplay between electrical and mechanical degrees of freedom at the nanoscale is of tremendous importance for both fundamental science and scientific techniques, and this fellowship will have impact on both of these. Although theory has gradually been developed, from an experimental perspective little is known about the mechanical interaction between atomically thin layers of materials and so this fellowship will try to close this gap. More specifically, each work package (friction, piezoelectricity, electromagnetic and thermal actuation, functional devices) will add to our current understanding of a very complex and multidisciplinary field of nanoelectromechanical systems.

To achieve the scientific goals of this fellowship existing techniques of micromanipulation of 2D crystals and fabrication of van der Waals heterostructures will have to be improved, and new (compatible with electromechanical measurements) fabrication technology for van der Waals heterostructures, has yet to be developed. Therefore, techniques developed in this fellowship will be beneficial for researchers, working in the field of nanofabrication and experimental solid state physics, both in higher education and in industrial R&D organisations.

Economic Impacts:
There is great potential for miniaturisation of machinery - by making nanoscale electromechanical devices all technology sectors will benefit, especially in the areas of wearable computers, self-powered devices, smart materials, sensors and telecommunication. In a long term, even more futuristic applications like industrial and medical nanorobots could become possible.

Additionally, large companies (e.g. Samsung, Nokia, IBM, Intel, Huawei, etc.) have expressed their interest in graphene/2D materials-related research for industrial applications. As nanoelectromechanical switches and resonators developed during this fellowship are most likely to find niche applications in wearable computers and self-powered sensors, this will have an impact on the development of related industries and will lead to future collaborations with potential industry partners. Thus, this fellowship will contribute to the development of a robust and competitive supply base in support of the emerging graphene/2Dmaterials-using industry, help companies to explore the realistic potential of graphene and nanomaterials for new products that have potential to disrupt the marketplace and building on the UK government investment of over £90m in the graphene sector.

Personnel Impact:
An EPSRC fellowship will be a major step towards my scientific independence, as this will give me more freedom to realize my scientific ideas and to build an independent research portfolio and develop my own research group with a view towards a permanent academic position, from where I hope I will be teaching students and training researchers of the future and advancing the frontiers of science for many years to come.

Societal Impacts:
The fellowship project will form an ideal platform for the training of early career researchers: my proposed programme incorporates several workpackages suitable for PhD students and postdoctoral researchers, both of whom will gain training in experimental and characterization techniques, device development, as well as transferable skills training. Moreover, the two postdocs, hired for this fellowship, will gain invaluable expertise during their work on this project, which will help them on their own scientific career pathways and strengthen their case for promotion.

Publications

10 25 50
 
Description 1) We initialised the ground-breaking work where we directly visualised graphene wave function and the chiral nature of graphene electrons (published in Science, 2016). This work offers unprecedented control over the quantum state of the electrons in graphene. The opportunity to control the pseudospin and chirality of electrons in graphene will expand the range of quantum phenomena studied in this remarkable material and, maybe one day will enable chirotronics, alongside with spintronics, valleytronics and electronics.
2) We started a new direction in graphene nanomechanics, where we demonstrated the transition of twisted graphene to perfect bilayer graphene by a self-rotation (published in 2D Materials, 2017). Our findings allow for precise control of the electronic properties of 2D crystals and their van der Waals heterostructures by nanomechanical engineering.
3) In collaboration with the researchers from the School of Chemistry and the School of Materials, we have rediscovered a naturally occurring van der Waals heterostructure: franckeite (published in Nature Communications, 2017). Franckeite opens new possibilities for energy storage applications such as solar energy and supercapacitors due to its excellent electrical conductivity and remarkable electrochemical properties.
4) Our research group discovered the quantum Hall effect in graphite films. Graphite is a well-studied material - its basic physics was already uncovered in the 1950s. It was believed to behave like a normal three-dimensional metal (semimetal, to be precise). At the same time, the quantum Hall effect requires two-dimensionality of electron gas - in three dimensions QHE is forbidden. Therefore, finding QHE in three-dimensional graphite - a system where it is the least expected was quite exciting. Another big surprise was that the quantum Hall effect in our system turned out to be very sensitive to an even/odd numbers of layers (even when the number of layers is above 100), completely changing the sequence of quantum Hall plateaux (Nature Physics, 2019).
5) In 2019, our research group developed a novel technology to produce films of rhombohedral graphite (published in Nanoletters, 2019). Of the two stable forms of graphite, hexagonal and rhombohedral, the latter, rhombohedral, is less stable and rarer. This precluded its previous detailed investigation, despite many theoretical predictions of the abundance of exotic interaction-induced physics. Our technology allowed us to study the transport properties in rhombohedral graphite films tens of graphene layers thick, unravelling the nontrivial physics of its topological surface states. Rhombohedral graphite is a completely new playground to explore strong electronic correlations, quantum criticality, and other exciting many-body phenomena, usually reserved for materials composed of f- or d-elements. A paper on the first-ever transport measurements on rhombohedral graphite has been published in Nature (2020).
6) In 2020, we developed a technology for in situ manipulations of van der Waals heterostructures for applications in twistronics (published in Science Advances, 2020).
Exploitation Route Results on chiral tunnelling of graphene (Science, 2016) presents a new technique for quantum technologies allowing unprecedented control over the quantum states of the electrons in graphene. Thermally-activated structural transition in bilayer graphene (2D Materials, 2017) brings a new tuning knob in the device technology of van der Waals heterostructures. A review on 2D materials and heterostructures (Science, 2016) consolidates the recent developments in the field and stimulates further progress in the growing field of nanoscience. Our work on rhombohedral graphite (Nature, 2020) introduces a completely new playground to explore strong electronic correlations, quantum criticality, and other exciting many-body phenomena, usually reserved to materials composed of f- or d-elements.
Sectors Digital/Communication/Information Technologies (including Software),Electronics,Energy,Manufacturing, including Industrial Biotechology,Other

URL http://www.2dmatters.com
 
Description Our research, funded by EPSRC Fellowship, allowed us to expand our work on novel crystalline materials towards demonstration of the potential of these materials to various applications to benefit UK science and industry. The next logical step of our research was to commercialise the scientific outcomes, which motivated us to seek support from ICURe to validate our business ideas. ICURE Award for our project "Bespoke crystals for open materials science" allowed our team to successfully test some of the business ideas, resulting in the incorporation of a spin-out company Bespoke Crystals Ltd, in 2019.
First Year Of Impact 2019
Sector Chemicals,Manufacturing, including Industrial Biotechology,Other
Impact Types Economic

 
Description (Programmable Matter) - New materials enabled by programmable two-dimensional chemical reactions across van der Waals gap
Amount € 2,748,476 (EUR)
Funding ID 865590 
Organisation European Commission 
Sector Public
Country European Union (EU)
Start 05/2020 
End 04/2025
 
Description Access to high-magnetic field facilities in Grenoble LNCMI
Amount € 36,000 (EUR)
Funding ID GSC12-218 
Organisation European Magnetic Field Laboratory 
Sector Academic/University
Country Belgium
Start 06/2019 
End 12/2019
 
Description EMFL
Amount € 36,000 (EUR)
Funding ID GSC16-216 
Organisation National Center for Scientific Research (Centre National de la Recherche Scientifique CNRS) 
Department Grenoble High Magnetic Field Laboratory
Sector Public
Country France
Start 06/2017 
End 12/2017
 
Description Edge terahertz photocurrent in graphene 
Organisation University of Regensburg
Country Germany 
Sector Academic/University 
PI Contribution Our group provided high-quality bilayer graphene field-effect transistors, performed characterisation and transport measurements, contributed to data analysis and discussions, and to the preparation of manuscripts.
Collaborator Contribution Our colleagues from the University of Regensburg performed and analysed photocurrent measurements, provided theoretical support, and prepared the manuscripts.
Impact two papers have been published: PRB 2020, PRB 2021
Start Year 2018
 
Company Name BESPOKE CRYSTALS LTD 
Description Bespoke Crystals Ltd focuses on bringing cutting-edge research to industrial applications. The company provides high-quality well-characterised crystals of metallic and layered compounds to academia and education, as well as for R&D labs in semiconductors, metallurgy, optoelectronics, quantum technologies, security, and jewellery industries. 
Year Established 2019 
Impact n/a
Website https://bespokecrystals.com/