Magnetocaloric effect in the layered organic–inorganic hybrid（CH_3NH_3）_2CuCl_4

We present a study of magnetocaloric effect of the quasi-two-dimensional（2D） ferromagnet（CH_3NH_3）_2CuCl_4 in ab plane（easy-plane）. From the measurements of magnetic field dependence of magnetization at various temperatures,we have discovered a large magnetic entropy change associated with the ferromagnetic–paramagnetic transition. The heat capacity measurements reveal an abnormal adiabatic change below the Curie temperature T_c~8.9 K, which is caused by the nature of quasi-2D layered crystal structure. These results suggest that perovskite organic–inorganic hybrids with a layered structure are suitable candidates as working substances in magnetic refrigeration technology.