Magnetic entropy change of the layered perovskites La_(2-2x)Sr_(1-2x)Mn_2O_7

摘要

Magnetocaloric properties of perovskite-type manganese oxides with double Mn-O layers of composition La_(2-2x)Sr_(1-2x)Mn_2O_7 (x=0.33 and 0.4) have been investigated. A broad peak of magnetic entropy change (-ΔS_M) was observed at the Curie temperature. The shape of -ΔS_M is strongly dependent on the Sr concentration. In contrast to Ln_(1-x)A_xMnO_3 perovskites, the distinct curvilinear shape of -ΔS_M for perovskites with double Mn-O layers shows different magnetic mechanisms arising from magnetocrystalline anisotropy.