Light-Induced Magnetization Changes in a Coordination Polymer Heterostructure of a Prussian Blue Analogue and a Hofmann-like Fe(II) Spin Crossover Compound

Abstract

Coordination polymer thin film heterostructures of the Prussian blue analogue Ni(II)b[Cr(III)(CN)6](0.7)·nH2O (NiCr-PBA) and the 3D Hofmann-like spin crossover compound Fe(azpy)[Pt(CN)4]·xH2O {azpy = 4,4'-azopyridine} have been developed, and spin transition properties have been characterized via SQUID magnetometry and Raman spectroscopy. The magnetic response of the ferromagnetic NiCr-PBA layer (T(c) ≈ 70 K) can be altered by inducing the LIESST effect (light-induced excited spin state trapping) in the coupled paramagnetic Fe(II) spin crossover material. Whereas an increase in magnetization is measured for the single-phase Fe(azpy)[Pt(CN)4]·xH2O, a decrease in magnetization is observed for the heterostructure. These results indicate the LIESST effect alone cannot account for the sign and magnitude of the magnetization change in the heterostructure, but the temperature profile of the magnetization shows that significant changes in the NiCr-PBA network are correlated to the spin state of the Hofmann-like SCO network.

Switchable molecule-based materials for micro- and nanoscale actuating applications: Achievements and prospects

“…This structure allowed them to convert the mechanical output of the SCO material into a bistable voltage signal. Conceptually similar results from the Talham [86] and Mascaros [87] groups prove that different strategies, based on the coupling of SCO strain with piezomagnetic, piezoelectric or piezoresistive materials may allow for multifunctionality and, as a perspective, for very useful synergetic responses.…”

Spin Crossover Nanomaterials: From Fundamental Concepts to Devices

“…In many cases the particles could be re‐dispersed in solvents and further processed to form films, surface patterns, and nanocomposite materials . Recently, more complex architectures, such as core–shell particles, multilayer films, hybrid plasmonic, and fluorescent SCO particles have been also synthesized attesting a certain degree of maturity of the field and providing scope for the development of multifunctional nanomaterials displaying synergistic effects. Let us mention also that conceptually related valence tautomeric and Jahn–Teller switch type molecule‐based nanomaterials have been also synthesized recently—raising similar fundamental questions and application ideas …”

Exchange coupling in an electrodeposited magnetic bilayer of Prussian blue analogues

“…Reversible switching of magnetization or magnetic pole inversion 19 mediated by different physical and chemical stimuli (visible light, 20,21 X-rays, 22 pressure, 23,24 and temperature 25 ) has been extensively reported. 29 In the present work, a sequential electrochemical approach has been applied for the fabrication of a PBA bilayer formed by a bottom layer of Cr 5 35,36 It is shown that this heterogeneous magnetic system shows proximity effects, such as exchange bias and exchangespring magnetism, which are characteristic of magnetic bi(multi)layers. Along this line, a remarkable example of ESM has been provided by core-shell nanoparticles based on PBA coordination networks.…”