KEr(MoO4)2 and CsDy(MoO4)2 - Low-Dimensional Ising Magnets

M. Kačmára, A. Orendáčováa, E. Čizmára, D. Horvátha, M. Orendáča, V. Bondarenkob, A.G. Andersb, A. Fehera and M. Jaščura a Faculty of Science, P.J. Šafárik University, Park Angelinum 9, 04154 Košice, Slovakia b Institute of Low Temp. Physics and Engineering, Lenin Avenue 47, 310164 Kharkov, Ukraine

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In the present work the behaviour of cluster excitations in magnetic field, B, parallel to the easy axis was experimentally studied by the measurements of KEr(MoO4)2 and CsDy(MoO4)2 specific heat, C, vs. B dependence studied at a constant temperature. Corresponding Monte Carlo simulations of C revealed that despite of the fact that the Ising exchange-coupling models proved useful for a sufficient description of the specific heat of these dipolar systems in B=0, the analysis of current experimental data requires a partial renormalization of exchange-coupling constants previously obtained from B=0 analysis. The influence of crystal field effects and long-range character of spin correlations is discussed.

DOI: 10.12693/APhysPolA.97.807 PACS numbers: 75.40.Cx, 75.10.Hk, 75.40.Mg