Exploring low-dimensional magnetism in cobalt vanadates, <i>A</i>CoV2O7 (<i>A</i> = Ca, Sr): Crystal growth and magnetic properties of effective spin-1/2 zigzag chains

We report the successful growth of high-quality single crystals of ACoV2O7 (A = Ca, Sr), a quasi-one-dimensional zigzag chain compound containing Co2+ ions, using the optical floating zone method. The crystal growth was stabilized under high-pressure argon–oxygen gas with slow growth rates, overcoming challenges associated with the incongruent melting behavior of this material. X-ray diffraction confirms the zigzag arrangement of Co2+ ions, forming a quasi-one-dimensional chain structure. Magnetic susceptibility and heat capacity measurements reveal an antiferromagnetic phase transition at the Néel temperature (TN ∼3.5 K) and negative Curie–Weiss temperatures, indicative of dominant antiferromagnetic interactions. The distorted CoO6 octahedral geometry and strong spin–orbit coupling suggest that Co2+ ions likely exhibit an effective J = 1/2 Kramers doublet state. The results presented here demonstrate the potential of ACoV2O7 (A = Ca, Sr) as a platform for investigating low-dimensional magnetism and quantum magnetic phenomena. These insights shed light on the role of the A-site ion in tuning the magnetic interactions, which will foster future research into the field-induced behavior in these cobalt vanadates.