Fig. 1: Charge-transfer bistability at room temperature.
a Pictures of 6 × 6 mm2 RbMn0.94Co0.06Fe thin films taken at room temperature, showing the colour change between the MnIII(S = 2)FeII(S = 0) low-temperature (LT) and MnII(S = 5/2)FeIII(S = 1/2) high-temperature (HT) phases. Starting from the LT phase, a persistent photoinduced phase transition (PIPT) is induced by laser excitation (120 W cm−2, 0.2 mm2 spot size, 3 s irradiation), as characterized through colour change at laser spot positions (green arrows). Subsequent heating of the irradiated film yields global colour change over the whole film in the HT phase. b Thermal hysteresis between the HT and LT phases, characterized through the χMT vs T plot, with the schematic representation of the electronic configurations showing the charge transfer (CT). c Streaming powder diffraction technique used for time-resolved measurements, performed on sub-µm crystals of RbMn0.94Co0.06Fe dispersed in solution and streamed through a liquid jet. The X-ray beam probes the sample at a time delay Δt after laser pumping within the hysteresis, which may eventually convert crystals from LT (blue) to permanent HT phase (red). The suspension in the reservoir circulates through a cooling device (230 K <\({T}_{\downarrow }\)), bringing crystals back to the ground LT phase, before injecting them anew at room temperature in the pump-probe beams.
