Magnetocaloric Effect in NiCl2(bipy) at Low Temperatures
K. Ráczová, E. Čižmár and A. Feher
Institute of Physics, Faculty of Science, P.J. Šafárik University, Park Angelinum 9, 041 54 Košice, Slovakia
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Magnetothermal properties of the compound NiCl2(bipy), where bipy = 4,4'-bipyridine, were studied. The single-ion anisotropy of Ni(II) ions was estimated and its influence on magnetocaloric effect in NiCl2(bipy) was investigated. Above the metamagnetic transition a maximum in the isothermal change of the magnetic entropy is reached near 11 K at field change from 0 T to 7 T with peak value -Δ S=6 J K-1 kg-1. The temperature dependence of Δ S above 7 K agrees with the assumed easy-axis type of single-ion anisotropy. The inverse magnetocaloric effect, typical for ordered antiferromagnets, was observed in the ordered state of NiCl2(bipy) only for isothermal magnetization in small fields up to 2 T.

DOI: 10.12693/APhysPolA.131.922
PACS numbers: 75.30.Sg, 75.30.Gw, 75.10.Pq