title: Precise electrochemical control of ferromagnetism in a cyanide-bridged bimetallic coordination polymer.
abstract: Magnetic coordination polymers can exhibit controllable magnetism by introducing responsiveness to external stimuli. This report describes the precise control of magnetism of a cyanide-bridged bimetallic coordination polymer (Prussian blue analogue: PBA) through use of an electrochemical quantitative Li ion titration technique, i.e., the galvanostatic intermittent titration technique (GITT). K(0.2)Ni[Fe(CN)(6)](0.7)·4.7H(2)O (NiFe-PBA) shows Li ion insertion/extraction reversibly accompanied with reversible Fe(3+)/Fe(2+) reduction/oxidation. When Li ion is inserted quantitatively into NiFe-PBA, the ferromagnetic transition temperature T(C) gradually decreases due to reduction of paramagnetic Fe(3+) to diamagnetic Fe(2+), and the ferromagnetic transition is completely suppressed for Li(0.6)(NiFe-PBA). On the other hand, T(C) increases continuously as Li ion is extracted due to oxidation of diamagnetic Fe(2+) to paramagnetic Fe(3+), and the ferromagnetic transition is nearly recovered for Li(0)(NiFe-PBA). Furthermore, the plots of T(C) as a function of the amount of inserted/extracted Li ion x are well consistent with the theoretical values calculated by the molecular-field approximation.
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), Umezono 1-1-1, Tsukuba, Ibaraki 305-8568, Japan.
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Mizuno
authors.forename: Masashi
authors.initials: M
authors.lastname: Okubo
authors.forename: Koichi
authors.initials: K
authors.lastname: Kagesawa
authors.forename: Daisuke
authors.initials: D
authors.lastname: Asakura
authors.forename: Tetsuichi
authors.initials: T
authors.lastname: Kudo
authors.forename: Haoshen
authors.initials: H
authors.lastname: Zhou
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Oh-ishi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Okazawa
authors.forename: Norimichi
authors.initials: N
authors.lastname: Kojima