Magnetic Single‐Ion Anisotropy and Curie‐Weiss Behaviour of Mg3V4(PO4)6

Abstract Direct current (DC) magnetometry data obtained for polycrystalline Mg 3 V 4 (PO 4 ) 6 were fitted by various magnetic models based on angular momentum basis states. As a result, single‐ion anisotropy of the magnetic V 3+ ions could be identified to decisively determine the magnetic properties of Mg 3 V 4 (PO 4 ) 6 and not antiferromagnetic exchange interaction between V ions as supposed in literature. It could be demonstrated analytically, by utilization of the Van Vleck equation, that also single‐ion anisotropy can lead to a linear and origin shifted inverse susceptibility curve in the high temperature region. The Weiss constant obtained from a Curie‐Weiss fit to such a susceptibility curve might falsely be ascribed to antiferromagnetic exchange interactions if additional low temperature magnetic properties are not considered for verification.