Institut de Chimie Moléculaire et des Matériaux d'Orsay

Post-doctorate fellow: Dr. Adelaida Trapali

Collaborations: ANR project 2D-Switch (2022-2026) lead par Vincent REPAIN

• Marie-Laure Boillot (ECI ICMMO), PhD thesis of Dr. Arthur Tauzin
• Jean-François Dayen (graphene devices, Institut de Physique et Chimie des Matériaux de Strasbourg)
• Vincent Repain, Amandine Bellec (surface caracterizations of the devices, Team "Matériaux et Phénomènes Quantiques", Paris)

Références:

• Journal of Materials Chemistry C, 2021, 9, 2712-2720

This project addresses the synthesis, characterization and fundamental understanding of a new family of active hybrid interfaces combining a 2D graphene (Gr) sensing layer in contact with an ultrathin film of switchable spin-crossover (SCO) sublimated molecules. To do so, we synthetize SCO molecules that can be sublimed under ultra-high vacuum conditions, stable upon deposition on surfaces (no chemical decomposition) and stable in air in the ultrathin film limit. We then study the 2D self-assembly and structure of ultrathin films (from 1 to 10 monolayers) of such molecules on graphene deposited on different substrates, and investigate the impact of the surface-molecule interaction on their switching properties (completeness of the transition, change of the transition temperature, light and electric field-induced switching). The switchable spin state of the molecular film is translated into a change of conductance of the graphene channel. The low temperature write/erase process of the conductive remnant states is implemented using two distinct excitation wavelengths, in the red (light-induced spin state trapping, LIESST) region for stabilizing the metastable paramagnetic state, and in the near infrared (reverse-LIESST) region for retrieving the stable diamagnetic state. The bistability of the system is confirmed over a significant temperature window through light-induced thermal hysteresis (LITH). These results demonstrate how the electronic states of insulating molecular switches can be stored, read and manipulated by multiple stimuli, while transducing them into low impedance signals, thanks to two-dimensional detectors, revealing the full potential of mixed-dimensional heterostructures for molecular electronics and spintronics. In continuing this work, we aim at studying how the SCO switching influence the electronic transport through the graphene layer, with the understanding of the transduction mechanism.

PhD student: Fatima Hamade

Funding ANR grant JCJC LECMA (2022-2025) lead by Nathalie Bridonneau

Collaborations :

• Pei Yu (ligands photoactifs, ECI ICMMO)

This research project aims at developing a molecular design that enables a light-induced electronic control of magnetic molecules. To do so, we intend to use light to trigger a change between two electronic states leading to bistability at room temperature. The molecules will consist of organic photo-active parts linked to Fe(II) spin crossover (SCO) complexes. These magnetic complexes can reversibly switch from a diamagnetic low spin state (LS, S=0) to a paramagnetic high spin state (HS, S=2). The concept developed consists in using light to induce a dissymmetric electronic distribution on the Fe(II) ligands that would trigger the spin transition process. To date, it still remains a challenge to reversibly and synergistically manipulate the SCO process by light irradiation in the solid state at room temperature. To aim at a direct control of the spin state, we will use organic photo-switches as ligands in SCO complexes, providing a change of the electronic density distribution in the coordination sphere of the magnetic metallic ion, thus triggering the spin switch. Thus, the molecular systems developed in this project open the way to information storage at the single molecule level at room temperature, and will have high potential in molecular electronics for the development of many applications such as sensors or electronic devices.