Photo-induced charge-transfer phase transition of rubidium manganese hexacyanoferrate in ferromagnetic and paramagnetic states

A charge transfer phase transition with thermal hysteresis loop is observed in a series of rubidium manganese hexacyanoferrates, RbMn[Fe(CN)(6)] (1), Rb0.88Mn[Fe(CN)(6)](0.96) center dot 0.6H(2)O (2), and Rb0.97Mn[Fe(CN)(6)](0.99) center dot 0.2H(2)O (3). This phase transition is accompanied by a structural change from cubic (F43m) to tetragonal (I4m2). Its high-temperature (HT) and low-temperature (LT) phases are composed of Mn-II(S = 2/5)NC-Fe-III(S = 1/2) and Mn-III(S = 2)-NC-Fe-II(S = 0), respectively. The phase transition is caused by a metal-to-metal charge transfer from Mn-II to Fe-III and a Jahn Teller distortion of the produced Mn-III ion. At the ferromagnetic state in LT phase of 2, the photo-induced phase transition is observed, i.e., magnetization is quenched by the irradiation with only one shot of laser pulse. This phenomenon is caused by a photo-induced phase transition from the LT phase to the HT phase. In 3, optical switching between LT and HT phases at room temperature in paramagnetic region is observed. (c) 2006 Elsevier B.V. All rights reserved.