Tuning of Transport and Magnetic Properties in Epitaxial LaMnO3+δThin Films

J Chen,W J Lu,Y P Sun,K J Zhang,L Hu,B Yuan,J M Dai

doi:10.1155/2014/218494

Abstract

The effect of compressive strain on the transport and magnetic properties of epitaxial LaMnO3+δthin films has been investigated. It is found that the transport and magnetic properties of the LaMnO3+δthin films grown on the LaAlO3substrates can be tuned by the compressive strain through varying film thickness. And the insulator-metal transition, charge/orbital ordering transition, and paramagnetic-ferromagnetic transition are suppressed by the compressive strain. Consequently, the related electronic and magnetic transition temperatures decrease with an increase in the compressive strain. The present results can be explained by the strain-controlled lattice deformation and the consequent orbital occupation. It indicates that the lattice degree of freedom is crucial for understanding the transport and magnetic properties of the strongly correlated LaMnO3+δ.

Highlights

IntroductionFor these LaMnO3+δ (0.085 ≤ δ ≤ 0.125) compounds, with decreasing temperature these samples exhibit transition from a paramagnetic insulator (PMI) to ferromagnetic metal (FMM) at TC, where the resistivity starts to decrease
Perovskite manganese oxides La1−xAxMnO3 (A = alkaline earth) have attracted a great deal of attention due to their interesting properties such as colossal magnetoresistance (CMR), charge/orbital ordering (COO), and insulator-metal transition (IMT) [1,2,3]
The results show that the in-plane compressive strain of the LaMnO3+δ/LAO exhibits a relaxation with the increase of film thickness

Summary

Introduction

For these LaMnO3+δ (0.085 ≤ δ ≤ 0.125) compounds, with decreasing temperature these samples exhibit transition from a paramagnetic insulator (PMI) to FMM at TC, where the resistivity starts to decrease. The samples undergo transition from FMM state to COO state at TCOO, while the resistivity shows an upturn. This COO phase coexists with the isotropic three-dimensional FM state in spite of the insulating behavior. Zheng et al found that the JT distortion of MnO6 reduces the charge coupling of the LaMnO3+δ thin film under an in-plane tensile strain on 0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 substrate [17, 18]. The effect of compressive strain on COO transition and FM transition of the films has been systematically investigated

Experimental

Results and Discussion

Conclusion