Van Vleck paramagnetism and enhancement of effective moment with magnetic field in rare earth orthovanadate EuVO4

The 4 f 6 systems were hypothesized to possess non-magnetic ( J = 0) ground state. However, all such systems have distinctly shown the presence of non-zero effective moment at low temperatures. In this context, a rare earth orthovanadate EuVO4, which in spite of having J = 0 ground state, possess non-zero magnetic moment. Our studies on EuVO4 reveal three different regions, having different features in magnetic susceptibility. The high temperature susceptibility exhibits linear dependence on temperature which arises due to inter-mixing of ground and excited states, followed by a temperature independent plateau-like region, ascribed to Van Vleck paramagnetism. At low temperatures, Curie-Weiss like behaviour is observed, which arise due to magnetic Eu2+ ions and results in non-zero effective moment. Our analysis reveals that the separation (A) between the J = 0 and 1 states decreases on increasing the external magnetic field which leads to an enhanced effective moment at higher fields. (c) 2023 Elsevier B.V. All rights reserved.

Automated summary

Although the 4 f 6 systems were expected to have a non-magnetic (J = 0) ground state, all such systems have shown the presence of a non-zero effective moment at low temperatures. In the case of the rare earth orthovanadate EuVO4, which has a J = 0 ground state, our studies reveal three different regions with distinct magnetic susceptibility features. The high temperature susceptibility is linearly dependent on temperature due to the inter-mixing of ground and excited states, while the temperature independent plateau-like region is attributed to Van Vleck paramagnetism. At low temperatures, a Curie-Weiss-like behavior is observed, resulting from the magnetic Eu2+ ions and leading to a non-zero effective moment. Our analysis shows that increasing the external magnetic field reduces the separation (A) between the J = 0 and 1 states, resulting in an enhanced effective moment at higher fields.