Excited Spin-State Trapping in Spin Crossover Complexes on Ferroelectric Substrates
Christian Wackerlin, Fabio Donati, Aparajita Singha, Romana Baltic, Silvio Decurtins, Shi-Xia Liu, Stefano Rusponi, and Jan Dreiser
The Journal of Physical Chemistry C 122, 8202 (2018)
Using X-ray absorption spectroscopy, we have studied thin films of Fe(II) spin crossover complexes deposited on differently poled ferroelectric PMN-PT substrates. The X-ray spectra reveal the temperature driven conversion between high-spin and low-spin states. X-rays induce excited spin-state trapping regime at 3 K, with large differences occurring between the two ferroelectric polarizations. We explain our findings by a modulation of the polarization-dependent efficiency of the scattering of X-ray-generated secondary electrons at the molecules. Our results provide a deep insight into the X-rays spin trapping mechanism and suggest that such molecules could be used as detectors for electrons traveling in the substrate at energies lower than the substrate electron affinity.