One-dimensional magnetism in copper phthalocyanine

Measurements of the proton spin-lattice relaxation rate, $T_1^{\mathrm{-}1}$, reveal that the organic insulator copper phthalocyanine Cu(PC) is a highly one-dimensional Heisenberg system. $T_1^{\mathrm{-}1}$ diverges as ${\omega }^{\mathrm{-}1/2}$ down to 11.4 MHz without evidence of cutoff. It was found that ‖J/$k_B$‖=0.286 K with the ratio ‖J/J’‖≥6×${10}^3$, where J and J’ are the intrachain and interchain exchange interactions, indicating that Cu(PC) is an excellent model one-dimensional Heisenberg magnet.