Structural, magnetic, electrical transport properties, and reversible room-temperature magnetocaloric effect in antipervoskite compound AlCMn3

We report the structural, magnetic, electrical transport properties, and magnetocaloric effect (MCE) of antipervoskite compound AlCMn3. It exhibits a second-order ferromagnetic-paramagnetic phase transition around (T-C) 287 K. The electronic resistivity (rho) shows a good metallic behavior except for a slope change around T-C. At lower temperatures (below 130 K), rho alpha T-2 indicates that the electron-electron scatterings domain. At evaluated temperatures (130-270 K), rho is linear dependence on temperature, implying that the phonon scatterings boost up greatly. Furthermore, a broad distribution of the magnetic entropy change (-Delta S-M) peak is found to about 100 K with the magnetic field change Delta H=45 kOe. The relative cooling power are similar to 137 J/kg and similar to 328 J/kg (or similar to 68 K-2 and similar to 162 K-2) with Delta H=20 kOe and 45 kOe, respectively. All these values are comparable with the typical MCE associated with a second-order transition. It suggests that AlCMn3 may be considered as a candidate material for near room-temperature magnetic refrigeration because of: (i) the large full width at half peak of the -Delta S-M-T curve, (ii) no hysteresis losses, (iii) the near room-temperature working temperature, and (iv) the low-cost and innoxious raw materials. Moreover, it is found that the simple theoretical model which only considering the magnetoelastic and magnetoelectronic couplings couldn't account well for the observed MCE in antiperovskite AlCMn3. (C) 2010 American Institute of Physics. [doi:10.1063/1.3505753]