B-site aluminum doping effect on magnetic, magnetocaloric and electro-transport properties of La0.7Sr0.3Mn1−xAlxO3

• The La0.7Sr0.3Mn1−xAlxO3 compounds are crystallized in a rhombohedral with R3¯c space group.
• Griffiths phase is observed in x = 0.15 and x = 0.2 samples.
• Theoretical work on magnetocaloric effect using phenomenological model in La0.7Sr0.3Mn1−xAlxO3 compounds.
• The CCDC model is valid for the electro-transport properties of x ⩾ 0.10 samples.
• The results of calculation are in a good agreement with the experimental data.

Magnetic, magnetocaloric and electro-transport properties of La0.7Sr0.3Mn1−xAlxO3 compounds in the composition range 0 ⩽ x ⩽ 0.2 were investigated. For x ⩾ 0.15 composition, it shows that the compounds with higher Al concentration show Griffiths phase-like behavior above the Curie temperature. The observed anomalous paramagnetic behavior is attributed to the existence of ferromagnetic clusters in the paramagnetic domain. Both the experimental and theoretical approaches were adopted to calculate the magnetocaloric behavior of Al-doped La0.7Sr0.3MnO3. The important parameters such as maximum entropy change, full width at half maximum, relative cooling power, and maximum adiabatic temperature have been explained qualitatively. Moreover, to understand the electrical transport properties of x ⩾ 0.1 samples, we applied phase-coexistence transport model, which depends on the coexistence and competition of ferromagnetic metallic phases and paramagnetic insulating phases. This model is in perfect agreement with experimental results over the whole range of temperatures studied.