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RESEARCH PRODUCT

Pressure induced increase in Tc for the organic-based magnet FeII(TCNE)2 (TCNE=tetracyanoethylene)

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Abstract Pressure dependent magnetization and 57Fe Mossbauer studies were performed on Fe(TCNE)[C4(CN)8]1/2·zCH2Cl2 (TCNE = tetracyanoethylene). Pressure did not influence the Mossbauer parameters in paramagnetic state. Mossbauer data reveals the onset of magnetic ordering at 130 K and significant enhancement of the magnetic ordering temperature from 100 to 150 K accompanied by an increase of the spontaneous magnetization, which is higher than reported from the magnetic data, and application of pressure induces the reversible formation of a new, metastable magnetic species. These changes suggest an increase of the dimensionality of magnetic interaction, i.e., stronger interlayer coupling. Application of 9.3 kbar increases Tc to 160 K, and the moderate dTc/dP of ∼1 K/kbar in the pressure-induced metastable state suggests a pressure-induced structural phase transformation that increases the number of next–nearest neighbors of iron.