A layered cobalt phosphonate exhibiting ferrimagnetism and slow magnetic relaxation

Abstract Compound Co 3 (hpyedpH) 2 (H 2 O) 4  · H 2 O ( 1 ) (hpyedpH 4  = 1-hydroxy-2-(3-pyridyl)ethylidene-1,1-diphosphonic acid) has a layer structure where chains of {Co 3 (hpyedpH) 2 (H 2 O) 4 } n are connected by {CPO 3 } tetrahedra, generating a layer containing 4-, 8- and 16-membered rings. Magnetic measurements show that compound 1 is a ferrimagnet with T c  = 3.8 K. Slow magnetic relaxation is observed below 3.8 K, possibly due to the domain wall movement.