Pressure response of three-dimensional cyanide-bridged bimetallic magnets

Effects of pressure on the structures and magnetic properties of three types of 3-D cyanide-bridged bimetallic coordination polymer magnets, (MnCrIII)-Cr-II ferrimagnet [Mn(en)](3)[Cr(CN)(6)](2)-4H(2)O (11; en ethylenediamine), (NiCrIII)-Cr-II ferromagnet [Ni(dipn)](3)[Cr(CN)(6)](2)-3H(2)O (2; dipn = N,N-di(3-aminopropyl)amine), and (NiFeIII)-Fe-II ferromagnet [Ni(dipn)](2)[Ni(dipn)(H2O)][Fe(CN)(6)](2)center dot 11H(2)O (3), were systematically examined under hydrostatic pressure up to 19.8 GPa using a piston-cylinder-type pressure cell and a diamond anvil cell. The ferrimagnet 1 showed the reversible crystal line-to-amorphous-like phase change, and the magnetic phase transition temperature (Tc) was reversibly changed from 69 K at 0 GPa to 126 K at 4.7 GPa. At higher pressure, the net magnetization was suppressed with increasing pressure, and the magnetic state at 19.8 GPa was assumed to be paramagnetic. The initial ferrimagnetic phase of 1 was not recovered after releasing the pressure from 19.8 GPa. The magnetic phase of 2 was reversibly converted between ferromagnetic and paramagnetic-like phase in the range 0 <= P <= 4.7 GPa while maintaining its crystallinity. The porous ferromagnet 3 was easily amorphized and irreversibly lost the ferromagnetic phase under low pressure (P <= 1.0 GPa). The flexible cyanide-bridged magnetic frameworks demonstrate well the pressure response as a reflection of differences in the magnetic structure and the framework strength in the GPa range.