High coercivity in a new molecular iron-based magnet

Abstract

A new molecule-based magnet containing Fe(II), Fe(III) and Cu(opba)2- (opba=ortho-phenylenebis(oxamato)) was synthesized. The samples were characterized by infrared spectroscopy, elemental analysis, atomic absorption, macroscopic magnetometry, X-ray diffraction, and 57Fe Moùssbauer spectroscopy. Magnetic measurements show that the compound presents a transition temperature below 15 K and a high coercivity, around 6.3 kOe at 4.2 K. At room temperature, the Moùssbauer spectrum is dominated by a broad doublet characteristic of Fe(II), and a small fraction of Fe(III) ions is also identified. At 4.2 K, the spectrum shows clear magnetic splitting.