Post-doc position (M/F) - Tailoring exciton physics at the sub-nanometer scale in twist-engineered van der Waals heterostructures – TEXTURES

24 Feb 2024
Job Information

Organisation/Company

CNRS

Department

Institut de physique et chimie des matériaux de Strasbourg

Research Field

Physics » Condensed matter properties
Physics » Solid state physics
Physics » Surface physics

Researcher Profile

First Stage Researcher (R1)

Country

France

Application Deadline

15 Mar 2024 - 23:59 (UTC)

Type of Contract

Temporary

Job Status

Full-time

Hours Per Week

35

Offer Starting Date

1 Oct 2024

Is the job funded through the EU Research Framework Programme?

Not funded by an EU programme

Is the Job related to staff position within a Research Infrastructure?

No

Offer Description

This postdoctoral project targets a comprehensive understanding and control of excitons (i.e., bound electron-hole pairs) in twisted van der Waals (vdW) heterostructures [1], i.e., stacks of 2D materials with a rotational misalignment. These systems exhibit moiré superlattices, wherein the electronic and optical properties are modulated with twist-tunable moiré wavelengths. Specifically, the recent observations of a rich variety of moiré excitons in twisted bilayers of 2D materials, in particular transition metal dichalcogenides (TMDs), lays the ground for AQMÉ. Engineering excitons and charge carriers in moiré superlattices holds huge promise for quantum nano-(opto)electronics; however, it comes up against major experimental difficulties. Indeed, the electronic and optical properties of vdW heterostructures are governed by intrinsic (twist angle, proximity effects) and extrinsic effects (defects, dielectric disorder, strain, atomic reconstruction), which all occur at the (sub)nanometer scale. Technological breakthroughs based on 2D materials require answers to the fundamental questions below:

- How do extrinsic disorder and moiré superpotentials modify the nanoscale optical properties of two-dimensional materials?
- How do excitons localize in moiré superpotentials? Are localized excitons coherently coupled with each other? What are their quantum optical properties?
- How can nano- and pico-second exciton dynamics be externally controlled at the nanoscale?

To address these questions, we will first fabricate and fully characterize ultraclean vdW heterostructures with finely controlled twist angle. Second, using a scanning tunneling microscope (STM) equipped with optical access, we will carry out optical spectroscopy and quantum photonics studies with state-of-the-art temporal resolution and unprecedented spatial resolution down to the atomic scale. Thereby, we will control quantum phenomena that are key in the development of future technologies based on moiré superlattices.

Selected references:
[1] N. Wilson et al., Nature 599, 383 (2021) - doi: 10.1038/s41586-021-03979-1
[2] K. Seyler et al., Nature 567, 66 (2019) - doi:10.1038/s41586-019-0957-1
[3] L.E. Parra Lopez et al., Nature Materials 22, 482 (2023) - doi:10.1038/s41563-023-01494-4 | Unistra and CNRS press release | news and views (doi:10.1038/s41563-023-01514-3) | preprint: arXiv:2204.14022

- Fabricate van der Waals heterostructures using cleanroom transfer methods.
- Perform optical characterization on these heterostructures
- Perform Scanning Tunnelling Microscopy (STM) measurements including Scanning tunneling spectroscopy
- STM-induced light emission, Tip-enhanced optical spectroscopy and nanoscopy
- Contribute to the STM setup maintenance
- Analyze and model experimental results.
- Contribute actively to the writing of scientific articles.

These tasks must be carried out independently, in regular interaction with the host team.

Integration into the host team and the local scientific community:
The project will be carried out at the The Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS, see below) within a tight collaboration involving the Nano Optics and Low-Dimensional Materials team (https://fcbg.team ) and the STM team (https://www-ipcms.u-strasbg.fr/stmipcms/ ). These two teams currently comprise five permanent staff members, two engineers, 4 PhD students, 2 Postdocs and Several MSc interns. In addition to the subject described above, we are developing highly complementary activities on opto-electro-mechanics in 2D materials, 2D magnetic materials (magno-opto-mechanics), atomic-scale photonics and magnetism. We interact with several of the laboratory's engineers and technicians, and are regular users of the STnano nanofabrication platform, where we assemble van der Waals heterostructures and fabricate 2D nano-resonators. As part of a transverse thematic axis, we actively collaborate with several colleagues at IPCMS and outside the laboratory (ISMO in Paris-Saclay, CESQ/ISIS in Strasbourg, LNCMI-Grenoble, LPCNO in Toulouse, Uni. Luxembourg, La Sapienza in Rome, EMPA Dübendorf, etc.). The thesis will naturally benefit from local synergies and our network of collaborations.
Our teams are actively involved in the HOWDI (low-dimensional van der Waals heterostructures), NS-CPU (Nanosciences with near-field microscopy under ultra high vacuum) research networks (called GDR in France).

About the IPCMS:
The IPCMS is a JRU (Joint Research Unit) between the CNRS & the Université de Strasbourg, with 30 years of history as a leading scientific institution at the interface between condensed matter physics, surface science, optics, material sciences, and chemistry. The CNRS is the largest interdisciplinary public research organisation in France, with more than 33,000 people working in +1,100 laboratories. Université de Strasbourg (Unistra) is one of the top French universities, hosting 4 Nobel Laureates and 1 Kavli Prize Laureate. Both CNRS & UNISTRA were awarded the HRS4R label in 2017. Since 2011, Unistra benefits from a national “Excellence Initiative (IdEx)”, which has been renewed in 2016. The most recognized areas of expertise of IPCMS are the design and fabrication of molecular and nanostructured or self-organized systems, nano-magnetism and magneto-electric coupling, spintronics, nano-electronics and optoelectronics, ultra-fast condensed matter processes, low-temperature near-field microscopy techniques, and transmission electron microscopy. Applications mainly cover new materials for information technology, health and energy. The laboratory is part of a cross-border regional context of scientific excellence in which it plays a structuring role with numerous European and international collaborations.
IPCMS is a key partner in a recently funded Interdisciplinary Thematic Institute (ITI) on quantum science and nanomaterials at Unistra (QMat). QMat associates an international graduate school and research funding that will provide numerous opportunities for the PhD candidates (teaching, tutoring, networking). State of the art workshops (mechanics, electronics), calculators, characterization platforms (electron microscopy, atomic force microscopy, surface characterization) and clean room (STnano) compose an ideal and stimulating environment to perform frontier research on 2D materials.
Unistra is a partner of the QuanTEdu France programme, a national teaching initiative on quantum science and technology).
Idex, ITI and QuanTEdu France are prestigious national fundings from the “PIA”: Investments for the Future programme), allocated for a period of 10 years.

Requirements

Research Field

Physics

Education Level

PhD or equivalent

Research Field

Physics

Education Level

PhD or equivalent

Research Field

Physics

Education Level

PhD or equivalent

Languages

FRENCH

Level

Basic

Research Field

Physics » Condensed matter properties

Years of Research Experience

None

Research Field

Physics » Solid state physics

Years of Research Experience

None

Research Field

Physics » Surface physics

Years of Research Experience

None

Additional Information
Eligibility criteria

- knowledge of the physics of two-dimensional materials
- general knowledge of condensed matter physics and light-matter interactions
- experience of working in cleanrooms (nanofabrication, strongly preferred)
- experience in experimental optics and optical spectroscopy
- expertise in scanning probe techniques, preferentially at low temperature under ultra-high vacuum
- expertise in electronic instrumentation
- very good level of English
- computer skills (programming, data analysis, interfacing)
Python (or Matlab or similar), LaTeX, Origin, Office pack or similar, Inkscape or similar

Additional comments

The candidate must have obtained a PhD degree in Physics. Applicants holding a PhD in Materials Science, Electrical Engineering or Mechanical Engineering could also be considered.
We are looking for a candidate with a solid background in fundamental physics and a strong taste for experimental research at the interface between condensed matter physics, optical spectroscopy and quantum photonics. The candidate will assemble and characterize vdW heterostructures, perform optical and STM-based measurements, data analysis and modelling.
He/she should be capable of working independently in a multidisciplinary environment and possess a curiosity-driven attitude.
A good command of written and spoken English is mandatory. Knowledge of French or willingness to learn the language is not mandatory but would be an asset.
The candidate must provide a letter of motivation, a detailed CV including a list of grades, and the contact information for one (or two) references.

Website for additional job details

https://emploi.cnrs.fr/Offres/CDD/UMR7504-CATBON-064/Default.aspx

Work Location(s)

Number of offers available

1

Company/Institute

Institut de physique et chimie des matériaux de Strasbourg

Country

France

City

STRASBOURG

Geofield

Where to apply

Website

https://emploi.cnrs.fr/Candidat/Offre/UMR7504-CATBON-064/Candidater.aspx

Contact

City

STRASBOURG

Website

https://www.ipcms.fr/

STATUS: EXPIRED