Universal field dependence of conventional and inverse magnetocaloric effects in DyCo2Si2

The rare-earth intermetallic compound DyCo2Si2 orders antiferromagnetically below TN = 23 K followed by a second magnetic anomaly at Tt = 9 K. The sample is known to show multiple metamagnetic transitions, which are reproduced in our present study. Our investigations on this sample indicate that the magnetocaloric effect (MCE) calculated from the magnetization data (in terms of change in entropy, ΔSM) is quite fascinating, and it is characterized by multiple sign reversals around TN and Tt. The MCE is found to be conventional (i.e., ΔSM is negative) above TN and below Tt, while it is inverse (i.e., ΔSM is positive) between TN and Tt. We performed a comprehensive analysis of the field dependence of the observed MCE, and a universal quadratic variation is observed at temperatures above and below TN (including the region below Tt) as long as the applied field is lower than the critical field for metamagnetic transition. The present work is able to show that the field dependence of the MCE in this antiferromagnetic material is quadratic despite the fact that the magnetocaloric effect is conventional or inverse in different temperature regions.