Monte Carlo simulation of the magnetocaloric effect in La2/3Ca1/3MnO3 single crystal

Abstract

The present work is devoted to a theoretical simulation study of the magnetocaloric effect in magnetically homogeneous La2/3Ca1/3MnO3 single crystal. Using the standard Monte Carlo-Metropolis algorithm and the classical Heisenberg model Hamiltonian, we have computed the two main magnetocaloric properties such as the isothermal entropy change and the adiabatic temperature change upon an abrupt variation of the intensity of the applied magnetic field, as function of temperature. A good qualitative agreement is observed between our simulation and experiment. We have shown that the maximum entropy change increases by increasing the intensity of the applied magnetic field. In addition, it occurs at the ferromagnetic-paramagnetic transition temperature regardless of the intensity of the applied magnetic field. Our simulation shows, moreover, that the adiabatic temperature change behaves as the isothermal entropy change with respect to the material temperature and the applied magnetic field variation. Quantitatively, however, the experimental data deviate more or less, depending on powder preparation conditions, from our simulation data. This demonstrates the deviation of the prepared powders with respect to an ideal magnetic structure, as expected experimentally. Our simulation expects a maximum isothermal entropy change of −5.2J/kgK and a maximum adiabatic temperature change of 5.7K under a magnetic field variation of 5T. On approaching room temperature, the magnitude of the magnetocaloric effect in La2/3Ca1/3MnO3 single crystal decreases but remains significant under a magnetic field variation of at least 2T.