Correlation between magnetocaloric effect and crystal growth in La1.4Ca1.6Mn2O7

We present systematic studies of calcium-doped lanthanum manganite La$_{1.4}$Ca$_{1.6}$Mn$_2$O$_7$ with differing preparation conditions, focusing on the ferromagnetic to paramagnetic transition. Particle size increased with sintering temperature, but the lattice constant remained unchanged. The discontinuity in heat capacity at $T_{¥rm C}$= 270 K showed a tendency to increase with rising heat treatment temperature. For the furnace-cooled sample at a heat treatment temperature of 1450 $^{¥circ}$C, the maximum magnetic entropy change was $¥Delta S_{¥rm max}$= 6.0 J/kg K at 255 K. However, for the quench-cooled sample at the same sintering temperature of 1450 $^{¥circ}$C, despite the grain size being almost identical, $¥Delta S_{¥rm max}$ was only two-thirds of this value.This suggests that factors other than particle size and porosity also influence magnetic scattering.