Syntheses and Magnetic-Properties of Zn-Diluted Sr-Based Perovskite Cobalt Oxides, Sr1−x Zn x CoO3; 0.05≤x≤0.3

Abstract

In order to check the solubility of Zn in the (Sr 1−x Zn x )CoO 3 perovskite structure and their research findings, several polycrystalline samples have been prepared under wide extreme synthesis conditions at 6 GPa/1300-1650°C. While 0.05 ≤ x ≤ 0.3 compositions revealed single phased cubic structure materials, x > 0.3 showed multiphased materials for (Sr 1−x Zn x )CoO 3 system. Like other substituted perovskite cobalt oxide systems (Ca, Y, Ho and Ce), the transport properties of the present materials show rather sizable changes with respect to 'x', although there are insignificant variations in lattice parameter and in Curie temperature, T c . All the present samples show soft ferromagnetism with T c in the range of 272-285 K for 0.05 ≤ x ≤ 0.3. The effective paramagnetic moment, P eff determined from the paramagnetic region decreases upon the substitution of Zn for Sr-site. These P eff (3.3-2.8 µ B /Co) values for 0.05 ≤ x ≤ 0.3 compositions seem to suggest that the Co 4+ lie in intermediate spin (IS) state for the present (Sr 1−x Zn x )CoO 3 series, although they are slightly smaller than those expected for IS-Co 4+ ; P eff = 3.87 µ B /Co. The electrical resistivity is found to increase with increase of 'x' for the investigated samples. The temperature and field dependence of both positive and negative magnetoresistance (MR) are noted for the Zn substituted samples. About 5% of -MR is observed for x = 0.05 sample around the transition temperature (280 K) under the field strength difference, H = 90 kOe. The present research findings are compared with our previous results on different perovskite cobalt oxides.

Investigation of bulk magneto-resistance crossovers in iron doped zinc-oxide using spectroscopic techniques

“…According to research, the BMR has both positive and negative elements that are caused by roving particles with different conductivities and motilities, as well as two-band spin splitting from spin dispersed itinerants with localized magnetic moments (Hsu et al, 2008;Chattopadhyay et al, 2013). The fluctuation in the relative intensities of the competing itinerant spin scattering processes is connected to the BMR transitions from negative to positive (Gacic et al, 2007;Balamurugan, 2012;Jansson et al, 2014;Can et al, 2016;Sapkota et al, 2016). The strength of spin scattering processes in doped magnetic oxides is affected by the amount of doping, the type of manipulated element, the type of doping, its solubility in the host-lattice, the concentrations of defects, the temperature, the applied magnetic field, the orbital overlap of the dopant, and the and the state-specific spin density (SDOS) (Wang et al, 2015a;Wang et al, 2015b;Lorite et al, 2015;Lv et al, 2015;Montes-Valenzuela et al, 2015;Lee et al, 2016;Mukherjee et al, 2017).…”