Influence of ferromagnetic thickness on structural and magnetic properties of exchange-biased manganite superlattices

Abstract

The structural and magnetic properties of superlattice structures of alternating ferromagnetic La23 Ca13 MnO3 (F-LCMO) and antiferromagnetic La13 Ca23 MnO3 (AF-LCMO) layers were systematically studied as functions of F-LCMO layer thickness, tF. Samples were grown via a high-oxygen pressure sputtering process. Magnetic hysteresis measurements after field cooling revealed an exchange bias, Hex, at low temperatures in such superlattices. We found a correlation of the structural and magnetic properties with tF. In particular, we observed diminished resistance, increased metal-insulator transition temperature, TMI, as well as increased Curie temperature with increasing tF. Additionally, we found that the temperature dependence of Hex* tF for superlattices with the same antiferromagnetic layer thickness, tAF, is a unique function and independent of tF. We also find that the low-temperature saturation magnetization, MS, follows a power-law dependence with temperature, according to M0 (1-B Tα) with an exponent of α=2.5±0.2. © 2006 American Institute of Physics.