Investigation of dynamic phenomena in spin crossover nanomaterials
(Studii asupra fenomenelor dinamice in nanomateriale cu tranzitie de spin)
Funded by Romanian Ministry of Research, Innovation and Digitization, CNCS/CCCDI-UEFISCDI, Project No. PN-III−P4-ID-PCE-2020-1946, within PNCDI III
Project Director: Prof. univ. dr. Cristian ENACHESCU
(Faculty of Physics, Alexandru Ioan Cuza University, Iași)
Aim
The project is devoted to the interaction with the light of the nanoscale thin films, and the time dependence of subsequent processes.
The coupling with phonons will be analysed in the framework of a new model, including the dynamic features of the crystal packing. This work brings the photo-switching of materials into a new perspective, different from the common approach, focused on electron and optical phonon dynamics at ultrafast timescales.
The aim of this project is to understand the switching and controlling the spins in molecular magnets in dynamic phenomena at nanoscale, to better handle and apply the properties of bistability and switching in devices using these materials.
The long-term perspective consists in clarifying the possibilities of their application for the high-density storage of information, or for their use as sensors and actuators. The systematic experimental studies will be correlated and interpreted by the simultaneous use of theoretical and numerical studies. The theoretical studies will be based on the experimental data and will be used not only to explain the observations, but also to propose new experimental procedures.
The central ideas of this scientific project are based on the fact that (i) the behaviour of nanoparticles embedded in various matrices or prepared as thin layers is different when comparing them to isolated micro and nanoparticles; (ii) the physics of ultrafast processes triggers a complex out-of-equilibrium dynamics involving different mechanisms occurring at different time and length scales, different than the ones observed under nanosecond irradiation. The understanding of the dynamical SC mechanisms is yet in its infancy, in both experimental (e.g. using optical microscopy and by ultrafast experiments), and theoretical details, the current project taking the challenge of these open questions.
Team
Objectives
(Objective 1) O1 Study of ultrafast phenomena in spin crossover systems
Experimental activities for objective 1
AE1.1 Synthesis of spin crossover systems of different sizes and shapes
AE1.2 Finding the optimum photoexcitation conditions (temperature, material amount etc.) for photomagnetic and optical measurements
AE1.3 Magnetic and optical measurements of photoexcitation and relaxation after photoexcitation of spin crossover nanoparticles and microparticles with different elastic properties (cooperativity)
AE1.4 Size and shape effects studies including photoexcitation, relaxation and light induced thermal hysteresis
AE1.5 Measurements of minor hysteresis loops during hysteresis induced by the light in order to find experimental FORC distributions followed by distribution analysis for understanding the dynamical change of interactions
AE1.6 Study of the combined roles of the external and environmental pressure for nanoparticles embedded in polymer or surfactant on the photoexcitation and relaxation
Theoretical activities for objective 1
AT1.1 Complex study of ultra-fast photoexcitation and relaxation using the elastic pattern, considering a combination of molecular and stochastic dynamics
AT1.2 Study of domain propagation during elastic stage for 2D and 3D samples, adjusting different relative time scales for spin dynamics and network relaxation
AT1.3 Preliminary studies for anisotropic effects using Ising-like models
AT1.4 Studies of effects to non-volatile transitions beyond transient states via the new developed elastic models considering various crystalline symmetry to predict elastic conversion time
(Objective 2) O2 Study of SC thin nanolayers deposited on substrates
Experimental activities for objective 2
AE2.1. The study of the thermal behavior based on magnetic and optical measurements on spin-crossover monolayers deposited on substrates with a priori fundamentally different interactions with the molecules, i.e. graphite, gold, and copper
AE2.2 Study of the effects of light irradiation as a function of the substrate in order to predict how the light affects the molecular correlations
AE2.3 Apply the FORC method to study interactions distributions as a function of the substrate
AE2.4 Study of the light effects on spin crossover thin films with ferromagnetic substrates
Theoretical activities for objective 2
AT2.1 Modelling the interactions with the substrate by a harmonic potential, using a triangular network of molecules
AT2.2 Elaborate and apply a new elastic model for various crystalline structures; comparison between the new model and the mechanoelastic model; check the dependence on the size and shape of the sample, and find pertinent parameters (spring constants, lattice parameter of the periodic anchoring points on the substrate)
AT2.3 Study how the cooperativity is modified by the molecule-substrate interactions, starting from a free-standing layer and increasing step-by-step the substrate coupling constant.
AT2.4 Quantify the cooperativity by measuring the molecular correlations, as in the experimental case, by calculating the local pressure and probability of switching in different neighboring environments (LS or HS or mixed states) for a direct comparison with experiments
Results
Reports:
Papers (click on the title for the paper)
- Author(s) Popa, AI; Stoleriu, L; Enachescu, C;
Title: Tutorial on the elastic theory of spin crossover materials
Source: JOURNAL OF APPLIED PHYSICS, Volume: 129, Issue: 13 Pages: 131101-1-131101-24, Published APR 7 2021
- Author(s) Plesca, D; Railean, A; Tanasa, R; Stancu, A; Laisney, J; Boillot, ML; Enachescu, C
Source: MAGNETOCHEMISTRY, Volume: 7, Issue:5 Article Number: 59 Published MAY 2021
- Author(s) Kelai, M; Repain, V; Tauzin, A; Li, WB; Girard, Y; Lagoute, J; Rousset, S; Otero, E; Sainctavit, P; Arrio, MA; Boillot, ML; Mallah, T; Enachescu, C; Bellec, A
Source: JOURNAL OF PHYSICAL CHEMISTRY LETTERS, Volume: 12, Issue: 26 Pages: 6152-6158 Published JUL 8 2021
- Author(s) Tong, Y; Kelai, M; Bairagi, K;, Repain, V; Lagoute J; Girard, Y; Rousset, S; Boillot, ML; Mallah, T; Enachescu, C; Bellec, A
Title: Voltage-Induced Bistability of Single Spin-Crossover Molecules in a Two-Dimensional Monolayer
Source: JOURNAL OF PHYSICAL CHEMISTRY LETTERS, Volume: 12, Issue: 45 Pages: 11029-11034 Published NOV 7 2021 (activitatea 1.6)
- Author(s) Hu, YW; Picher, M; Tran, NM; Palluel, M; Stoleriu, L; Daro, N; Mornet, S; Enachescu, C; Freysz, E; Banhart, F; Chastanet, G
Source: ADVANCED MATERIALS, Article number 2105586 Published OCT2021 (activitatea 1.6)
- Author(s) Amanoloaei, G; Stoleriu, L; Stancu, A;
Title: Dynamic Stoner–Wohlfarth Model for Time-Dependent Magnetization Analysis
Source: IEEE MAGNETICS LETTERS, Volume 12 (2021) (activitatea 1.4)
- Author(s) Chakraborty, P; Sy, M; Fourati, H; Delgado, T; Dutta, M; Das, C; Besnard, C; Hauser, A; Enachescu, C; Boukheddaden, K
Source: PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Volume: 24, Issue: 2 Pages: 982-994 Published JAN 4 2022 (activitatea 2.1)
Author(s) Ati, M ; Enachescu, C ; Bouamrane, R
Title: Molecular Dynamics Study of Oscillators Spin Chain in Framework of Variable Interaction Range Model
Source: ACTA PHYSICA POLONICA A, Volume: 141, Issue: 3 Pages: 191-197 Published MAR 2022 (activitatea 2.3)
Author(s) Volte, A; Mariette, C; Bertoni, R; Cammarata, M; Dong, X; Trzop, E; Cailleau, H; Collet, E; Levantino, M; Wulff, M; Kubicki, J; Yang, FL; Boillot, ML; Corraze, B; Stoleriu, L; Enachescu, C; Lorenc, M
Source: COMMUNICATIONS PHYSICS, Volume: 5, Issue: 1 Article Number: 168 Published JUN 29 2022 (activitatea 2.4)
Conferences
- Alexandra-Ioana Chilug, Cristian Enăchescu, Laurentiu Stoleriu, Pradip Chakraborty, Cooperativity in mixed spin crossover molecular magnets analyzed through a mechanoelastic model, TIM Conference, Timisoara, noiembrie 2022 (prezentare orală, activitatea 2.1))
- Radu Tanasa, Diana Plesca, Denis Morineau, Jerome Laisney, Alexandru Stancu, Cristian Enachescu, Marie-Laure Boillot, Calorimetric First Order Reversal Curves (FORCs) for spin crossover systems, European Conference on Molecular Magnetism, Rennes, iulie 2022 (poster, activitatea 2.2 și activitatea 2.5)
- Cristian Enachescu, Laurentiu Stoleriu, Masamichi Nishino, Seiji Miyashita, Roman Bertoni, Herve Cailleau, Eric Collet, Maciej Lorenc, Tyler Haddock, Renske van der Veen, Mechanoelastic simulations of ultrafast photoswitching dynamics in spin crossover systems, European Conference on Molecular Magnetism, Rennes, iulie 2022 (prezentare orala, activitatea 2.4)
- Enachescu, D. Plesca, A. I. Chilug, A. Railean, L. Stoleriu, MECHANOELASTIC MODEL FOR SPIN-CROSSOVER MOLECULAR MAGNETS, TIM Conference, Timisoara, noiembrie 2022 (prezentare orala, activitatea 2.4)
- Cristian Enachescu, Alexandra-Ioana Chilug, Anastasia Railean, Laurentiu Stoleriu, Thermo- mechano-elastic model and lattice dynamics in molecular spin crossover systems, Molecular trends in Molecular Magnetism conference, Kharagpur, India, decembrie 2022 (prezentare orala, activitatea 2.4)
- Cristian Enachescu, Anastasia Raileana Laurentiu Stoleriu, Massine Kelai, Amandine Bellec, Vincent Repain, Marie-Laure Boillot, Talal Mallah, Modelling spin crossover layers on substrates in the framework of an elastic approach with self-adjustable interactions, European Conference on Molecular Magnetism, Rennes, iulie 2022 (prezentare orala, activitatea 2.6)