Creation of organic radical ferromagnetic crystals with Curie temperatures at the 30 K level

Abstract

The high-pressure magnetic properties of an organic radical ferromagnet including Se atoms were studied by vibrating-coil SQUID magnetometry. The magnetic state at a pressure (P) of approximately 2 GPa has the highest Curie temperature (T_C) at approximately the 30 K-level, and the analysis using mean-field theory demonstrates that an ideal three-dimensional ferromagnetic interaction network is realized there. The value of T_C observed by ac magnetic measurements is consistent with that obtained by vibrating-coil SQUID magnetometry below approximately 4 GPa. For P ＞ 6 GPa the magnetic network may be described in terms of a one-dimensional ferromagnetic chain with predominantly antiferromagnetic lateral (interchain) interactions, in accord with the results of density functional theory calculations.