Magnetocaloric effects from an interplay of magnetic sublattices in Nd₂NiMnO₆

Abstract

We present a combined experimental and theoretical study to understand the magnetism and magnetocaloric behavior of the double perovskite Nd2NiMnO6. The magnetic susceptibility data confirms a ferromagnetic transition with K. An additional feature at T = 25 K, indicative of antiferromagnetic correlations, is present. A positive magnetocaloric effect (MCE) near and a negative MCE around T = 25 K is inferred from the temperature dependence of the change in magnetic entropy at low magnetic fields. The negative MCE peak is suppressed on the application of a magnetic field and can be made to switch to a conventional positive MCE upon increasing magnetic field. We understand and reproduce these features in Monte Carlo simulations of a phenomenological Heisenberg model for Nd2NiMnO6. The validity of the model is tested using density functional theory calculations. We argue that this simple understanding of the experimental observations in terms of two antiferromagnetically coupled sublattices allows these results to be useful across a broader class of magnetocaloric materials.

Rotating magnetocaloric effect in the ferromagnetic Weyl semi-metal Co3Sn2S2

“…Figure 5(b) shows results of such a power law fitting to the −∆S max M vs H data. The fit gave the value for the power law exponent n = 0.603 (5). The expected value for n within a Mean field model is 2/3 27 .…”

“…The successful construction of a universal magnetocaloric curve indicate that the PM-FM transition is a second order magnetic transition. Powr law dependencies of the magnetic entropy change and RCP were found and yield the power law exponents n = 0.603 (5) and m = 1.213 (12), respec-tively. These values are consistent with values of the critical exponents reported in a previous critical behavior study on polycrystalline Co 3 Sn 2 S 2 .…”

“…If magnetization data is available only at closely spaced discrete values of temperature, as is mostly the case in experiments, the integral in the above expression is replaced by a summation 5 . The -∆S M vs T curves for both the cases show broad peaks around T c = 174 K. The maximum value of −∆S M at 9 T is 1.6 J/kg-K along the c-axis, while it is 0.8 J/kg-K in the ab plane.…”

“…The magnetocaloric effect (MCE) has been a topic of sustained attention for the last two decades due to its potential application in magnetic refrigeration [2][3][4][5] . Providing an environmental friendly alternative to conventional gases is one of the main advantage of this technique.…”

A magnetocaloric study on the series of 3d-metal chromites ACr$_{2}$O$_{4}$ where A = Mn, Fe, Co, Ni, Cu and Zn

“…Generally, the rare-earth-based compounds have a large effective magnetic moment and show a giant magnetocaloric effect [29][30][31] . A lot of experimental, theoretical work has been carried out to understand the magnetocaloric behavior of rare-earth-based materials 32,33 . The rare-earth-based based materials are expensive and get sometimes get oxidized in air.…”