Electron-lattice coupling and double exchange effects to improve TCR of La0.67-xNdxCa0.25Sr0.08MnO3 films grown on La0.3Sr0.7Al0.65Ta0.35O3 substrates

Abstract

In this study, La0.67−xNdxCa0.25Sr0.08MnO3 (LNCSMO, x = 0.09, 0.10, 0.11, 0.12) films were prepared by sol-gel spin coating method. The results indicate that the LNCSMO film is oriented and grown on a La0.3Sr0.7Al0.65Ta0.35O3 (LSATO) (00l) substrate. In addition, with the increase of Nd3+ content, the Mn-O bond length (dMn-O) and Mn-O-Mn bond angle (θMn-O-Mn) decreases. The concentration ratio of Mn4+ increases firstly and then decreases, and resulting in an enhanced and then weakened double exchange (DE) effect. Measuring the variation of sample resistivity with temperature (ρ-T) using the standard four-probe method. As the content of Nd3+ increases, the metal-insulator transition temperature (Tp) gradually decreases, and the resistivity (ρ) gradually increases. The replacement of Nd3+ makes the peak temperature coefficient of resistivity value (TCRmax) of the material firstly increase and then decrease. At x = 0.11, the TCRmax reaches 34.28% K-1 at 254.72 K. This provides new insights into the impact of Nd doping on electrical transport properties.