Low-field magnetocaloric effect in single crystals controlled by magnetocrystalline anisotropy.

The influence of magnetocrystalline anisotropy (K) on the magnetic entropy change (ΔS_M) in single crystals under low fields (H) is studied based on unbiased Monte Carlo simulations. When H is applied perpendicular to the easy axis, the positive and negative ΔS_M may coexist. The positive ΔS_M peak value and its maximum value optimized by the field and the threshold of switching to negative ΔS_M depend on K. Moreover, K linearly enhances the blocking temperature where the negative ΔS_M maximum is obtained, associated with the decrease in the peak value with increasing K. Finally, the rotating ΔS_M under a constant H may be much larger than ΔS_M produced by moving the model in and out of the same H, and the best response to K is found at 86° between K and H, independent of the anisotropy magnitude. [ABSTRACT FROM AUTHOR]