Light-induced phase separation in the [Fe(ptz)₆] (BF₄)₂spin-crossover single crystal

Abstract

-We present novel insight on like-spin domains (LSD) in cooperative spin transition solids by following the photo-transformation and the subsequent relaxation of a [Fe(ptz)6](BF4)2 single crystal in the vicinity of the light-induced instability. Self-organization under light is observed, accompanied by Barkhausen-like noise and jumps which reveal the presence of elastic interactions between LSDs. The light-induced phase separation process is discussed in terms of a dynamic potential providing spinodal instability in the corresponding temperature range. This useful concept is applicable to all types of switchable molecular solids.

X‐ray Absorption Spectroscopy as a Probe of Photo‐ and Thermally Induced Valence Tautomeric Transition in a 1:1 Cobalt–Dioxolene Complex

“…The most reasonable explanation for this behavior is that the VT process involves nucleation-like phenomena with the formation of phase boundaries characterized by slightly different structural and electronic parameters during the transition. [43] This would confirm the hypothesis made on the partial resolution of the molecular structure obtained by single-crystal X-ray diffraction experiments at different temperatures. [20] As a second characterization step we focused our attention on the investigation, by XAS, of the conversion of this VT complex by light irradiation.…”

Complete Direct and Reverse Optically Induced Valence Tautomeric Interconversion in a Cobalt–Dioxolene Complex

“…[17,18] The presence of two distinct Co centers in the lattice is confirmed by the solution of X-ray structures at 100 and 160 K (Figure 2), even if we could only obtain a partial refinement [25] due to the probable formation of spin-like domains. [26] Notwithstanding these limitations, we can safely conclude that at both temperatures the asymmetric unit consists of two crystallographically independent [CoA C H T U N G T R E N N U N G (Me 2 tpa)-…”

The interaction between the spin transition and a crystallographic phase transition in the spin-crossover compound [Fe(bbtr)3](ClO4)2: Nucleation, formation of domains and fluctuations

“…LS relaxation even slows down as the thermal transition temperature of 100 K is approached. This can only be explained by quite large short-range interactions leading to fluctuations and the formation of clusters or domains of equal spins [33,36,37]. Fig.…”