The effect of pressure on the magnetic properties of the ferromagnetic mixed-valence Prussian blue analogue CsFeII[CrIII(CN) 6] has been studied by magnetic susceptometry. The abrupt spin crossover transition at T1/2↓ = 207 K, induced by the change of FeII from the high spin (HS) (t2g4e g2, S = 2) to the low spin (LS) (t2g 66eg0, 5 = 0) configuration shifts to higher temperatures in a rigid fashion at a rate of 60 K kbar-1 with an unchanged width of the thermal hysteresis loop (ΔI = T1/2↓ - T1/2↓ ≈ 35 K). At the same time, the ferromagnetic transition temperature increases quasilinearly with increasing pressure at a rate of 0.1 K kbar-1. Infrared spectroscopic measurements under pressure reveal that the FeII-N-C-CrIII structural motif is preserved in the course of the internal spin rearrangements and no linkage isomerization of the cyanide bridge accompanies the spin crossover phenomenon. Conversion to the FeII LS state is initially incomplete with a minority of inhomogeneously distributed FeII HS domains surviving at ambient and low pressures. Their fraction rapidly decreases under compression until at ∼5 kbar all FeII is in the LS state. The observed piezomagnetic response is reversible upon decompression.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films