Oxygen‐deficiency‐induced suppression of JT distortion and stabilization of charge ordering in La0.2Sr0.8MnO3−δ
Year: 2014
Type: article
Abstract: Structural phase‐transition studies employing low‐temperature transmission electron microscopy and low‐temperature X‐ray diffraction have been carried out on nearly stoichiometric (δ = 0.01) and on off‐stoichiometric (δ = 0.12) versions of La0.2Sr0.8MnO3−δ manganite. The nearly stoichiometric La0.2Sr0.8MnO3−δ undergoes a cubic to Jahn–Teller distorted C‐type antiferromagnetic tetragonal phase transition at 260 K. For off‐stoichiometric La0.2Sr0.8MnO3−δ the Jahn–Teller distorted tetragonal phase transition is totally suppressed and the basic perovskite lattice remains cubic but shows a charge‐ordered phase. Stabilization of charge‐ordered phase in the absence of cooperative Jahn–Teller distortion has been attributed to Coulomb repulsion and Hunds coupling energy. The off‐stoichiometric sample shows characteristically different physical properties. This has been realized through transport, magnetic, and calorimetric measurements. A smooth crossover from variable‐range hopping transport to a power‐law dependence of resistivity (ρ) on temperature (T), i.e., ρ = CT−α has been realized. This has been attributed to multistep inelastic tunneling through channels involving localized states around oxygen vacancy sites.
Source: physica status solidi (b)
Authors: Aga Shahee, R. J. Choudhary, R. Rawat, N. P. Lalla
Institution: UGC DAE Consortium for Scientific Research
Language: English
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2012392438