engleski

Magnetoelectric multiferroic guanidinium copper(II) formate

Multiferroic guanidinium copper(II) formate, [C(NH2)3][Cu(HCOO)3], belongs to the family of metal organic perovskites with the formula ABX3. It crystallizes in the orthorombic space group Pna21 and consists of copper – formate 3D framework with guanidinium cations in its nearly cubic cavities. Due to the Jahn-Teller effect of Cu2+ ion, the octahedral coordination is elongated, producing the framework of Cu-formate chains in the c direction, where Cu2+ ions inside the chain are linked with short bonds and Cu ions between the chains with the long bonds. We have studied magnetic properties of [C(NH2)3] [Cu(HCOO)3] using MPMS5 SQUID magnetometer. Temperature dependence of magnetization showed a broad peak centered at 45 K which can be ascribed to antiferromagnetic order in the Cu-formate chains. Below 4.6 K the sharp rise of magnetization indicated a formation of 3D spin canted antiferromagnetic long range order. Hysteresis loops at the temperatures below 4.6 K showed a sharp increase of magnetization for the fields lower than 50 Oe. Anisotropy could be seen in both M(T) and M(H) measurements. The effect of electric field on the magnetization was observed at temperatures below 4.6 K as a difference in magnetization curves measured with and without the applied electric field, pointing to the existence of substantial magnetoelectric coupling. Search for the explanations of observed magnetic and magnetoelectic behaviour is in progress considering the interesting crystal structure of this compound. Wishing for better understanding we are collaborating with other scientists doing the complementary research such as the ab-initio calculations and torque anisotropy measurements. It would also be interesting to do electron paramagnetic resonance experiments and optical measurements in order to see if there is magnetoelectric response at much higher frequencies making it possible choice for the application as a fast magnetoelectric.

multiferroics ; magnetoelectrics ; perovskites ; metal-organic compounds

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