PhD in Proximity effect with charge density waves (M/F)

Job Description

Thesis Subject

A charge density wave is a spatial modulation of the electronic density in a crystal, and is associated to periodic lattice distortions. Frölich and Peierls introduced theoretical descriptions of these phenomena in the 1950s. Since then, these peculiar electronic states never ceases to intrigue: their connection with the superconducting state remains an open question, and often (as they are discovered in new classes of materials), the mechanism for their formation remains ill-understood. When two materials are put in contact, one hosting a charge density wave and the other not, the charge density wave should leak out in the second material. This proximity effect, the alter ego of that observed for instance in magnetism and optics, has been predicted in the 1990s [see Vissher & Bauer, Phys. Rev. B 54, 2798 (1996) ; Banerjee, Haurie & Pépin, Phys. Rev. B 107, 115152 (2023)]. However, it has not yet been demonstrated experimentally. The research hypothesis of the PhD work in that certain single-layer crystals represent ideal platforms to make this demonstration. The work will focus on transition metal disulfide crystals, some of which develop charge density waves at low temperatures, and others not. The goal will be to grow the materials from the bottom-up, and to seek signatures of the charge density wave, including the one generated by proximity. To do so, we will look for optical evidences, of these collective excitations. The kind of evidence is known since the 1970s but are more challenging to obtain with ultra-thin materials. We will also seek for signs of phonon softening with temperature, which might indicate the appearance of the charge density wave, and will track the ordre parameter of the periodic lattice distorsion as function of temperature. Measurements will be done by Raman scattering spectroscopy and electronic diffraction at variable temperature.

The candidate will have a strong background in solid state physics. Strong taste for experimental physics.

Your Work Environment

The work is integrated in a collaboration ANR project, involving four teams in Grenoble, Paris and Saclay. The consortium expertise covers growth of materials, near field microscopy, optical spectroscopy and diffraction, as well as ab initio methods. Frequent interactions between the partners are planned.

Institut NÉEL is a CNRS unit (UPR 2940) under agreement with the University Grenoble Alpes. The laboratory is related to the CNRS Physique. It is located in Grenoble, in the heart of a unique scientific, industrial and cultural environment. It is one of the largest French national research institutes for fundamental research in condensed matter physics enriched by interdisciplinary activities at the interfaces with chemistry, engineering and biology. It consists of 450 employees, including 175 researchers.
CNRS is a public, scientific and technological organization.
The core mandate is to identify, to carry out or to have carried out, either alone or with partners, all research that advances science or contributes to the country's economic, social, and cultural progress. Internationally recognized for the excellence of its scientific research, the CNRS is a reference in the world of research and development, as well as for the general public.

The candidate will work at the Institut Néel with the team: QUEST/Quan2m - "2D quantum states with tunable interactions".

Compensation and benefits

Compensation

2300 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

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