Charge-Transfer-Induced Spin Transitions in Crystals Containing Cyanide-Bridged Co–Fe Clusters: Role of Intra- and Intercluster Interactions

Abstract

A theoretical model has been developed to explain at the electronic level the charge-transfer-induced spin transition (CTIST) in crystals based on cyano-bridged binuclear Fe-Co clusters. The CTIST is considered as a cooperative phenomenon (phase transformation) driven by the long-range electron-deformational interaction via the acoustic phonons field that is taken into account within the mean field approach. The model for CTIST includes also the metal-metal electron transfer and intracluster magnetic exchange. The conditions that favor the CTIST are discussed. The qualitative explanation of the experimental data is given.

Electric‐Field Control of Magnetic and Polarizability Properties of Cyanide‐Bridged Fe–Co Clusters

“…In these surroundings, both the Co III and Fe III ions are diamagnetic. The states of the isolated Fe–Co clusters with localized electrons arise from their three configurations, which are presented below . For each configuration, the individual spins of the ions in the cluster are also indicated [Equation ]. …”

“…In the unique state originating from configuration I, the total cluster spin S n = 0; in the states of configuration II, S n = 0, 1; and S n = 1, 2 for configuration III (Figure ). The states of configurations I and II with S n = 0 are coupled by electron transfer . The total number of these states is seven, including the only state arising from configuration I and six states originating from configuration II (Figure ).…”

“…a model was developed to describe the magnetic characteristics and Mössbauer spectra of the cyanide‐bridged pentanuclear {[Os(CN) 6 ] 2 [Fe(tmphen) 2 ] 3 } cluster exhibiting CTIST. In ref . a model crystal containing cyanide‐bridged Fe–Co clusters as a structural element was examined, and the interplay between the intracluster Co–Fe electron transfer and cooperative interactions was analyzed.…”

“…a model crystal containing cyanide‐bridged Fe–Co clusters as a structural element was examined, and the interplay between the intracluster Co–Fe electron transfer and cooperative interactions was analyzed. The common feature of the models suggested in refs , . is the allowance for the different elasticity of intra‐ and intercluster spaces and the assumption that the electron‐deformational interaction accompanying the transitions (ls‐Fe II )(ls‐Os III )→(hs‐Fe III )(ls‐Os II ) and (ls‐Fe II )(ls‐Co III )→(ls‐Fe III )(hs‐Co II ) is responsible for the cooperative phenomena.…”

Photomagnetic molecular and extended network Langmuir–Blodgett films based on cyanide bridged molybdenum–copper complexes

“…1,2 Such materials, capable of persistent photo-induced changes in their magnetization via processes such as spin crossover or charge transfer induced spin transition (CTIST), have received considerable attention in the last few years. [15][16][17][18][19][20] Among several smart photomagnetic materials being investigated, promising groups are the cobalt-iron Prussian blue analogues [21][22][23] as well as the molybdenum-copper octacyanometallates. [9][10][11][12][13][14] To go one step further, these light-switchable bistable compounds might be viewed as promising platforms for information storage through their integration in devices.…”