Observation of Second-Order Phase Transition in Canted Antiferromagnet α-Cu₂V₂O₇ Using Magnetocaloric Effect

Understanding thermomagnetic phase transitions in frustrated magnetic materials is a complex problem. Herein, we study the canted antiferromagnet pyrochlore (α-Cu2V2O7) and uncover a second-order phase transition (SOPT) through magnetocaloric effect. The corroboration for this transition is rationalized by qualitative and quantitative magnetic data analysis. The first-order phase transition is ruled out owing to the extinction of thermal hysteresis and the existence of positive slopes in H/M vs M2 Arrott plots, in agreement with Banerjee criterion. The manifestation of a "caret" type shape, a fingerprint of SOPT, in the three-dimensional plots of temperature evolution of entropy change (ΔSM) with the applied field (H) is observed. Captivatingly, the locally assessed H and T dependence of n(T,H)=dln|ΔSM|dlnH curves follow n ∼ 1 at lower T, n ∼ 2 at higher T, and a minimum value at TN. But just after the TN, the value of n(T,H) is noticed to not exceed 2, evidently expounding the SOPT, and it is concomitant with qualitative analysis. From a future perspective, the experimental techniques can be exploited to study the phase transition along the different orientations of diverse frustrated magnetic materials in epitaxial thin films or single crystals that could exhibit appealing magnetic phenomena.