Structural and electrical properties of gadolinium-substituted La0.6−xGdxSr0.4MnO3 (x = 0–0.3)

Effect of K+ doping on the structure, magnetic, and magnetocaloric properties of La0.65Ca0.35-xKxMn0.95Ni0.05O3 (x = 0, 0.05, 0.10, 0.15, 0.20) manganites

The effects of Li substitution on structural, magnetic properties, and electroresistance (ER) behaviour in La0.8Na0.2-xLixMnO3 (x = 0 – 0.15) manganites prepared via the conventional solid-state method were reported. All samples exhibited a metal–insulator transition behaviour with a decrease in the metal–insulator transition temperature, TMI from 270 K (x = 0) to 255 K (x = 0.15) and reduction in Curie temperature, TC from 272 K (x = 0.10) to 235 K (x = 0.15). All samples exhibited a reduction in resistivity under higher applied current of 5 mA than that of 1 mA, which led to an ER effect. Large ER value of −59 % is achieved for sample × = 0.15 at 300 K, thereby indicating its potential application for spintronic-based devices. The competition between the occurrence of lattice distortion and the presence of magnetic inhomogeneity induced by A-site disorder (σ2) is suggested responsible for the observed ER effect. 

Effects of Li substitution on structural, magnetic properties and electroresistance behaviour in La0.8Na0.2-Li MnO3 monovalent-doped manganite

The effects of K+ substitution at the Ba-site on the structural, magnetic, and electrical properties and magnetoresistance (MR) of La0.7Ba0.3−xKxMnO3 (x = 0 and 0.04) manganites prepared via the solid-state method were investigated. Rietveld refinement of X-ray diffraction data confirmed that both samples were crystallized in the rhombohedral structure with the R3c¯ space group. In addition, the unit cell volume, V, and the average grain size also increased with K+ ions. Magnetization versus applied field (M–H) measurement was carried out, and the saturation magnetization (Ms) was found to increase from 1.81 μB/f.u. (x = 0) to 4.11 μB /f.u. (x = 0.04), implying that K+ ions strengthened the ferromagnetic (FM) interaction. Furthermore, the metal–insulator transition temperature, TMI, increased from 257 K (x = 0) to 271 K (x = 0.04). The observed behaviour may be related to the enhancement of double-exchange (DE) interaction due to the increase in Mn-O-Mn bond angle and electronic bandwidth (W), favouring the increasing rate of the eg electron hopping process. The fitting of the electrical resistivity data in the metallic region describes the significance of residual resistivity, electron–electron and electron–magnon scattering processes to elucidate the electronic transport properties. Within the insulating region, variable range hopping (VRH) and small polaron hopping (SPH) models are proposed to describe the conduction mechanism.

https://www.mdpi.com/2410-3896/7/3/51/pdf?version=1661418375

Amirah Zahrin

Papers

Structural, Magnetic, Electrical Properties and Magnetoresistance of Monovalent K-Substituted La0.7ba0.3- X K X Mno3 (X = 0 and 0.04) Manganite