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• First-ever magnetic Compton profiles (MCPs) of non-stoichiometric Ni 0.9-x Pr x Fe 2.1 O 4 inverse spinel ferrites. • Decomposed experimental MCPs into constituent profiles of Ni, Fe, Pr-4f and diffuse electrons. • Validated MCP based total and site-specific spin moments using FP-LAPW calculations. • Explored role of orbital magnetic moments using MCP data and magnetization data. • Revealed effect of Pr-4f states in amending the spin moments and electronic properties. Magnetic Compton profiles of 5 % and 15 % Pr-doped non-stoichiometric NiFe 2 O 4 have been measured using synchrotron radiations of energy 182.65 keV at SPring-8, Japan. An analysis of MCPs measured at 6 and 300 K show that the total spin moment decreases with increasing temperature and Pr concentration in Ni 0.9-x Pr x Fe 2.1 O 4 which is consistent with the magnetic moment (spin + orbital) as observed from magnetization measurements data. Spin moments at different sites are deduced using decomposition of MCPs in the elemental profiles of Ni, Pr-4f, Fe and diffused electrons. Spin moments at Ni-site have been found to play crucial role in emergence of absolute spin moments. Spin moments at Pr-site is aligned antiparallel to that of Ni and Fe sites. The orbital magnetic moment is also deduced from the subtraction of MCP based spin moments from the magnetization data. Theoretical FP-LAPW based total and atom specific spin moments are found in consonance with the MCP based data. Total and spin projected density of states are also computed using the FP-LAPW method to validate role of Pr-4f and Fe-3d (O h) states in amending the total magnetic moment with Pr concentration. The M−H based saturation magnetization derived at 6 and 300 K temperature show that the saturation magnetic moments reduce from 2.21 → 2.05 μ B /f.u. at 6 K and 2.10 → 1.98 μ B /f.u. at 300 K with increase in Pr concentration from 5 % → 15 %. On the basis of hysteresis curve and coercive force, both the doped compounds show soft magnetism. [ABSTRACT FROM AUTHOR]

• Measured spin momentum densities for Ni/Co doped LCMO using synchrotron radiations. • Elaborated peculiarities of magnetism using experimental MCPs and DFT computations. • Revealed mixed valence states of Mn and its ferromagnetic interaction with Ni and Co. • Explored Z-in and Z-out JT distortion in LCMO and after Ni and Co doping. • Disseminated guidelines for interpretation of MCP data using ab-initio computations. Magnetic Compton profiles (MCPs) of La 0.7 Ca 0.3 Mn 0.95 (Ni/Co) 0.05 O 3 between 8 and 250 K have been measured using high energy inelastic scattering at SPring-8, Japan. For a quantitative analysis on amendment of magnetic properties, temperature-dependent experimental MCPs are decomposed into constituent profiles related to Mn, Ni/Co and itinerant (diffuse) electrons. Decomposed profiles unambiguously show that Mn-3d electrons are ferromagnetically coupled with Ni/Co ions while itinerant electrons are linked anti-ferromagnetically with Mn-3d and Ni/Co-3d electrons. An annotation of MCP and VSM data depicts that the orbital magnetic moments are anti-ferromagnetically coupled to total spin moments. Variation in magnetic response in undoped and Ni/Co doped perovskites is devoted to formation of mixed valence states of Mn atom. The spin contribution at different sites are found to be in tune with present density functional theory (DFT) based calculations which are thoroughly analyzed on the basis of changes in the e g and t 2g states of Mn, Ni/Co caused by Jahn-Teller distortion. Present MCP data and DFT calculations set guidelines to probe the reliable origin to examine magnetic response and half-metallic properties of such manganites. [ABSTRACT FROM AUTHOR]