Influence of ferroelectric layer on artificial multiferroic LSMO/BTO bilayers deposited by DC and RF sputtering

Abstract

La$_{2/3}$Sr$_{1/3}$MnO$_3$ (LSMO)/BaTiO$_3$ (BTO) bilayers were deposited on (001) SrTiO$_3$ substrates via DC and RF sputtering at pure oxygen atmosphere at a substrate temperature of 830$^{\circ}$C. We studied the structural, electrical and magnetic properties on LSMO/BTO bilayers, when LSMO thickness is fixed at 40 nm and BTO thickness is varied from 20 to 100 nm. Reciprocal Space Maps in LSMO show a strained growth for all samples, while BTO layers are always relaxed. Magnetization and electrical measurements indicate the influence of the ferroelectric layer, due to saturation magnetization increases from 500 to 590 emu/cm$^3$ and coercive field decreases from 178 to 82 Oe with BTO thickness. Mean Field mechanism is identified on all samples with critical exponent $ \beta $ between 0.42 and 0.54. Resistivity measurements show electron-electron and magnon- magnon scattering conduction mechanisms. The influence on magnetic and electrical properties of bilayers with BTO thickness is attributed to crystallographic strains at the interface and the corresponding relaxation with increasing BTO layer thickness.