Detailed magnetic and structural properties of exchange‐biased La_1‐xCa_xMnO₃

Abstract

We measured structural, magnetic and, magneto-transport properties of heterostructures consisting of La 1-x Ca x MnO 3 ferromagnetic (FM) layers (x = 0.33) and antiferromagnetic (AF) layers (x = 0.67). We grew FM/AF superlattices via a high-pressure sputtering technique on (001) oriented SrTiO 3 substrates. We systematically varied the thickness of the ferromagnetic layers, while maintaining a fixed thickness of the antiferromagnetic layers. Alternatively, we also varied the thickness of the antiferromagnetic layers, keeping a fixed ferromagnetic layer thickness. The total superlattice thickness was kept approximately constant. XRD analysis confirms the existence of the superlattice structure by the observation of multiple satellite peaks around the (00l) manganite Bragg reflections. We extracted the average lattice parameter of the superlattice and its dependence on the thicknesses of the ferro-and antiferromagnetic layers. We conducted field cooling (FC) and zero field cooling (ZFC), magneto-thermal, and magneto-resistance measurements. The existence of an exchange bias effect at temperatures below the Néel temperature of the AF layer was revealed by magnetization loops measured after FC. We studied the dependence of magnetic parameters on the thicknesses of the ferro-and antiferromagnetic layers. We found that the structural, magnetization, and magneto transport properties as functions of F-layer thickness are all correlated.