Magnetic, thermal and transport properties of phase-separated La0.27Nd0.4Ca0.33MnO3

The magnetic, resistive and thermal properties of the phase-separated compound La0.27Nd0.4Ca0.33MnO3 have been experimentally studied. The sample is found to experience a charge/orbital ordering transition at similar to 175 K and an antiferromagnetic (AFM) transition at similar to 156 K without a magnetic field. A magnetic field stabilizes the ferromagnetic ( FM) order and the field-induced FM phase coexists with the AFM phase under a field below 2 T in the temperature range below TC approximate to 110 K. However, the magnetic entropy change accompanying the AFM-FM transition is negligibly small when T-C < T-N, grows rapidly as TC approaches TN under the driving of an applied field, and saturates at a value of similar to 4 J kg(-1) K-1 when T-C > T-N. A general relation between resistivity and magnetization, rho = A(0)T exp[(epsilon - 800m(2))/T] ( m = normalized magnetization), is established for the paramagnetic phase, which is also applicable to other compounds with different characters, such as the La0.67Ca0.33MnO3 film and the La0.474Bi0.193Ca0.33Mn0.994Cr0.006O3 and Eu0.55Sr0.45MnO3 ceramics. In the FM state, the resistivity is quite sensitive to the change of spin alignment and exhibits an exponential decrease with magnetization rho = rho(0) exp(- 22.7m). Field-induced phase separation is believed to be responsible for the distinct properties of La0.27Nd0.4Ca0.33MnO3.