Electrical and magnetic transport in Strontium doped Europium Ferrimanganites

Eu_0.65Sr_0.35Fe_xMn_1−xO₃ (x=0.1, 0.3 and 0.5) has been prepared using a standard solid state reaction method. The under-investigation compounds is found to crystallize in a single-phase orthorhombic structure in the P_bnm space group (62). The adiabatic polaron electronic transfer was obtained for all samples and the activation energy of x=0.1 sample is equal to 1.013 meV and slightly increase at x=0.3 (1.289 meV) while is doubled for x=0.5 to be 2.1065 meV. The magnetization–temperature dependence measurements of Eu_0.65Sr_0.35Fe_xMn_1−xO₃ show the ferromagnetic ordering at low iron concentration x=0.1 and when iron concentration increase to x=0.5 the noncollinear magnetic ordering (the canted antiferromagnetic) is obtained. The magnetic phase transition (paramagnetic-ferromagnetic transition) in the Eu_0.65Sr_0.35Fe_0.1Mn_0.9O₃ is observed at T_c of 150 K. For Eu_0.65Sr_0.35Fe_0.5Mn_0.5O₃ the multi-magnetic phase transition is observed at T_c of 200K and T_N of 430 K. The resistivity at low temperature is measured. Theoretical Calculations using Monte Carlo code have been done. The magnetization as function of temperature has been calculated using Monte Carlo simulations for Eu_0.65Sr_0.35Fe_xMn_1−xO₃ (x=0.0, 0.1, 0,2, 0.3, 0.4 and 0.5). Ising model is a suitable model to study the magnetization for our compounds. The internal energy for x=0 is the highest value compared with the other x values which have nearly a ground state value equal to 2.7 J. - Highlights: • The distortion parameter in the crystal structure of Eu_0.65Sr_0.35Fe_xMn_1−xO₃ increase with increasing concentration of iron and affected both electrical and magnetic transport. • The density of electrons over the unit cell decrease with increasing the iron concentration and thus give rise to the decrease in electrical conductivity and the change of the magnetic ordering. • The transition from thermal activation mechanism at temperature higher than room temperature into adiabatic polaron mechanism at temperature lower than room temperature in all samples. • The transition from the soft FM ordering at low iron concentration x=0.1 into the harder canted FM ordering with x>0.3. • The internal energy calculation showed the highest value of x=0, compared with the other x values, which have nearly a ground state value equal to 2.7 J