Third Funding Period 2024-2027:
A04 Spin+Phonons: Exploring the interplay between spins and phonons of spin crossover materials and single-molecule magnets
Prof. Dr. Volker Schünemann (Department of Physics, RPTU)
Prof. Dr. Eva. Rentschler (Institute of Physics, JGU)
The project explores spin state switching in purposeful designed chiral and racemic spin crossover (SCO) molecules and molecular materials. Special focus is on light excited spin states and the identification of phonon modes, which are believed to steer the spin crossover process in these materials. For this purpose, we will measure iron density of phonon states with nuclear inelastic scattering (57Fe NIS) also in non-equilibrium conditions using sub-ns time resolved NIS and perform density functional theory calculations. In addition, we aim to identify phonons responsible for unwanted under barrier spin relaxation in Dy containing single molecular magnets using 161Dy NIS experiments.
Second Funding Period 2020-2023:
A04 Spin+Phonons: Exploring the interplay between spins and phonons in micro- and nanostructures of spin crossover materials
Prof. Dr. Volker Schünemann (Department of Physics, RPTU)
Within project A04, the spin crossover (SCO) process in iron(II) containing SCO nanostructures will be investigated for non-equilibrium conditions, induced by ultrashort laser pulses in the fs time regime using novel ns optical pump- NIS (nuclear inelastic scattering) probe and ultrafast fs pump-probe photoelectron spectroscopy techniques. In this way, we will achieve a deeper physical understanding of spin switching in SCO materials by exploring the phonon mediated first order phase transition, which involves coupling of the electron spin to the molecular lattice. In addition, we aim to identify phonons responsible for unwanted under barrier spin relaxation in single molecular magnets using 161Dy NIS experiments.
First Funding Period 2016-2019:
A04 Spin+Phonons: Exploring the interplay between spins and phonons in micro- and nanostructures of spin crossover materials
Prof. Dr. Volker Schünemann (Department of Physics, RPTU)
Project A04 aims for a deeper physical understanding of phonon mediated first-order phase transitions. Within this project the temperature induced spin state change of iron(II) spin crossover (SCO) compounds will be investigated by means of surface sensitive Mössbauer spectroscopy as well as with synchrotron based nuclear forward scattering (NFS). A special focus will be on the investigation of the spin dependent density of phonon states of SCO nanostructures in comparison to those of 1-D, 2-D and 3-D iron(II) polymers and single molecular crystals. In this way it will be possible to clarify whether hysteresis effects are size dependent on the nanoscale and whether they differ in zero-dimensional (dots), one dimensional (tubes) or two dimensional nanostructures (thin films). A special focus lies on materials which exhibit SCO at room temperature and in which the spin state change is addressable via light. In this way also the spin switching process itself will be investigated by means of ultrafast fs-pump-probe photoelectron spectroscopy techniques in order to explore spin dependent spatiotemporal dynamics.
Aim 1: Understand the interplay between spins and phonons of spin crossover materials from the solid state down to the nanometer scale
Aim 2: Clarification of the spin dependent spatiotemporal dynamics in nanostructures and thin films of SCO materials after light excitation