Griffiths phase-like and its evolution with calcium-deficiency in La0.65Ca0.35MnO3 system

In this paper, we report the magnetic properties of Ca vacancies in La0.65Ca0.35−x□xMnO3 (0 ≤ x ≤ 0.15) powder samples synthesized using the sol–gel reaction. Rietveld refinement of powder X-ray diffraction data reveals that all samples crystallize in the orthorhombic structure with Pbnm space group. Then, the magnetic properties of these compounds are discussed in detail, building on the magnetization and the susceptibility. The temperature dependence of magnetization reveals a magnetic transition from ferromagnetic to paramagnetic phase when increasing temperature. The inverse of magnetic susceptibility shows a downturn with decreasing temperature before the Curie temperature TC indicating the existence of Griffiths phase for the temperature range TC ≤ T ≤ TG, where TG is the Griffiths temperature, which proves the existence of ferromagnetic clusters in the paramagnetic domain. Furthermore, by investigating the magnetocaloric parameters, the field dependences of $${{{\Delta}}}S_{M}^{{Max}}$$ and RCP can be expressed by the power laws, $$\Delta S_{M}^{{max}}$$ ≈ a (µ0H)n and RCP ≈ b (µ0H)m, where a and b are coefficients, n and m are the field exponents, respectively.