Vol.:(0123456789) 1 3 Applied Physics A (2019) 125:775 https://doi.org/10.1007/s00339-019-3079-6 Existence of Grifths Phase and magnetocaloric efect in electron doped Ca 0.85 Gd 0.15 MnO 3 Bidyut Sarkar 1  · Rinku Sarkar 1  · Ripan Nag 1  · Sudipta Pal 1 Received: 19 August 2019 / Accepted: 14 October 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract Occurrence of Grifths Phase (GP) and magnetocaloric efect have been investigated in Ca 0.85 Gd 0.15 MnO 3 (CGMO). The doping of Gd at Ca site interrupts the long-range antiferromagnetic ordering of the parent sample CaMnO 3 and induces ferromagnetism. Both the Arrott plot study and the estimated Landau coefcients signify that the paramagnetic to ferromag- netic transition is a second-order phase transition at 113 K. GP inhomogeneity is noticed from the analysis of temperature- dependent inverse susceptibility curves. Observed Grifths Phase behavior is suppressed with increasing magnetic feld strength. In addition, the CGMO sample exhibit magneto caloric efect and the maximum magnetic entropy change is found to be 2.525 J kg −1  K −1 for magnetic feld change of 50 kOe. 1 Introduction Electron doped manganites RE x Ca 1−x MnO 3 (x = 0.15) where RE = Nd, Dy, Sm etc. show interesting physical properties like magnetic reversal, magnetocaloric efect, magnetic phase transition etc. [1–3]. CaMnO 3 is G-type antiferro- magnetic in nature with Neel temperature T N = 125 K [4]. When Ca cation is partially replaced by tri-valent rare-earth ion (RE 3+ ), a ferromagnetic component develops due to double exchange interaction and antiferromagnetic order- ing diminishes i.e. ferromagnetism and anti-ferromagnetism coexist in Ca 0.9 Pr 0.1 MnO 3 manganite [5]. Again diferent type of phase inhomogeneity is observed in electron doped manganite. Low-doped CGMO manganite exhibits fasci- nating magnetic behavior including magnetization reversal in the low temperature and the isothermal magnetization curve exhibits insignifcant hysteresis loop [6]. The study of magnetocaloric properties is interesting for searching a suitable material to work suitably in magnetic refrigeration where the magnetic entropy change is large. In the present report, we have investigated the magnetic and magnetoca- loric properties of CGMO polycrystalline manganite. The nature of magnetic phase transition of CGMO compound has been identifed from the estimated values of the Landau coefcients. 2 Experimental Polycrystalline sample CGMO was synthesized by stand- ard solid state reaction path. Starting materials were CaO, Gd 2 O 3 and Mn(CH 3 COO) 2 , 4H 2 O with 99.99% purity from Sigma Aldrich. The ingredients were mixed in weight ratio 1:1.7534:9.0165 respectively. The mixture was heated for 6 h at 873 K and next at 1173 K for 12 h using electric mufe furnace. The product was grounded and pressed into disc shaped, and sintered at 1373 K for 12 h in air. The process was repeated at 1473 K for 12 h and was cooled down by natural cooling in air atmosphere. X-ray difraction (XRD) measurement was performed at RIGAKU difractom- eter with Cu-K α radiation at room temperature. XRD data was collected for 2θ range 20°–80° with the step of 0.02°. XRD data were analysed by Rietveld refnement method with FULLPROF suit software taking pseudo-Voigt pro- fle function [7]. Magnetization measurement was done in SQUID magnetometer (5 T) from 2 to 330 K. The mode of data collection of magnetization versus temperature (M–T) measurements were zero field cooling (ZFC) and field cooled cooling (FCC) with the temperature range 5–300 K at respective applied feld (H). Magnetizations versus feld (M–H) data were recorded in the feld range of 0–50 kOe * Sudipta Pal sudipta1@klyuniv.ac.in 1 Department of Physics, University of Kalyani, Kalyani, Nadia, W.B. 741235, India