Observation of the magnetic criticality and the magnetocaloric effect in LaMn2Si2 in the vicinity of the phase transition around the room temperature

Highlights: • The magnetic properties of LaMn₂Si₂ have been studied using the Monte-Carlo simulation. • The ferromagnetic transition temperature (T_C) is 311 K, which agrees with the experimental value (310 K). • The RCP value is 82 J/kg for LaMn₂Si₂, indicating good magneto-caloric materials. • The T_C of the Cu doped LaMn₂Si₂ (LaMn_1.8Cu_0.2Si₂) has gone down to 281 K with the 78 J/kg RCP value. • The critical constants ($\alpha =0.302$, $\beta =0.328$, $\gamma =1.293$) are nearly same as the 3D-Ising model. In search of the ideal candidate for the room temperature magnetic refrigerator, we found that this ternary intermetallic LaMn₂Si₂ is very useful for this purpose. So, the detailed magnetic properties and the critical behaviour around the phase transition have been studied through the Monte Carlo simulation process. The critical temperature of LaMn₂Si₂ is 311 K, which is the same as the previous experimental study. The temperature-dependent magnetic susceptibility, magnetic specific heat, Binder cumulant and the internal energy have been calculated to confirm the phase transition temperature. The critical exponents are determined through the finite-size scaling method at the critical temperature. The values of $\alpha ,\beta$ and γ are 0.302, 0.328 and 1.293, respectively, similar to the 3D-Ising model. The entropy change and the adiabatic temperature change are determined to study the magnetocaloric effect. The relative cooling power (RCP) is 82 J/kg for 6 Tesla applied fields. We then doped 10% Cu in the Mn site to reduce the critical temperature to 281 K and similarly studied the magnetocaloric effect. The RCP value turns out to be 78 J/kg. However, this compound will be a good candidate for the magnetic refrigerator at room temperature without emitting the greenhouse gas.