Critical Exponent Analysis and Evidence of Long-Range Ferromagnetic Order in Lightly Pr-Doped Nanocrystalline (La 1-x Pr
- PDF / 2,721,153 Bytes
- 12 Pages / 439.37 x 666.142 pts Page_size
- 103 Downloads / 156 Views
Critical Exponent Analysis and Evidence of Long‑Range Ferromagnetic Order in Lightly Pr‑Doped Nanocrystalline (La1‑xPrx)0.67Ba0.33MnO3 (x = 0.15 and 0.22) Manganites Ma. Oumezzine1 · E. K. Hlil2 Received: 26 April 2020 / Accepted: 23 July 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract We investigate the effect of lightly P r3+ doping ions on the critical behavior of (La1-xPrx)0.67Ba0.33MnO3 (x = 0.15–0.22) perovskite synthesized by the modified sol–gel Pechini method. The obtained critical exponents (beta, gamma and delta) have been investigated by measuring the magnetization around the Curie temperature, TC. Based on the modified Arrott plot and Kouvel–Fisher techniques, scaling hypothesis, and critical isotherm analysis, we have determined the critical exponent values characteristic of magnetic order of (La1-xPrx)0.67Ba0.33MnO3 (x = 0.15–0.22), with β = 0.55–0.49, γ = 1.06–1.01, and δ = 2.702–3.299. These values indicate that the magnetic order due to lightly Pr3+ doping exhibits long-range ferromagnetic ordering. This fact is in good agreement with the mean-field model. In addition, the exchange interaction is obtained as J(r) ~ r4.56 and ~ r4.49 for 15-at. % Pr and 22-at., respectively. We argue that the range of interaction extends beyond the nearest neighbors. Keywords Critical behavior · Perovskite manganite · Mean-field model · Magnetization
1 Introduction The doped rare-earth manganites with perovskite structure having general formula R1−xAxMnO3 (R is the rare-earth ion such as Nd, La, Pr, and Sm, whereas A are trivalent rare earth and divalent alkaline earth ions like Pr, Ca, Ba, Te, etc.) have pulled a keen interest of researchers because of the close correlation between * Ma. Oumezzine [email protected] 1
Laboratory of Physical Chemistry of Materials, Faculty of Sciences of Monastir, University of Monastir, 5019 Monastir, Tunisia
2
Institut Néel, CNRS, Université Grenoble Alpes, B.P. 166, 38042 Grenoble, France
13
Vol.:(0123456789)
Journal of Low Temperature Physics
their charge-spin-orbital-lattice degrees of freedom [1, 2]. These materials exhibit many interesting properties like paramagnetic (PM)-ferromagnetic (FM) phase transition (PM-FM), colossal magnetoresistance (CMR), the magnetocaloric effect (MCE) (related to a large magnetic entropy change) and the strong correlation between structural and magnetic properties [1–4]. It should be noted that the manganites are of particular interest, as it exhibits large La3+ Ba2+ Mn3+ Mn4+ O2− x x 3 1−x 1−x MR above room temperature. Near x = 0.33, this system shows ferromagnetic behavior [5]. The substitution of a smaller P r3+ ion for L a3+ enhances the microstructural inhomogeneity and leads to more chemical/structural disorder in second-order magnetic systems [6–8]. This certainly enhances electronic localization, resulting in the decrease of the mobility of e g electrons. In addition, this could affect the Curie temperature TC and saturation magnetization [9, 10]. However, the mixed-
Data Loading...
