Spin/Orbital Modulation in Perovskite Manganite Superlattices

<jats:title>Abstract</jats:title><jats:p>A systematic study is presented for structural characterization and physical properties of two kinds of perovskite oxide superlattices composed of ferromagnetic (FM) and antiferromagnetic (AF) layers. Spin ordering structures is modulated in FM La<jats:sub>0.6</jats:sub>Sr<jats:sub>0.4</jats:sub>MnO<jats:sub>3</jats:sub>/<jats:italic>G</jats:italic>-type AF La<jats:sub>0.6</jats:sub>Sr<jats:sub>0.4</jats:sub>FeO<jats:sub>3</jats:sub> superlattices, whereas, ordering structures both in spin and orbital are modulated in La<jats:sub>0.6</jats:sub>Sr<jats:sub>0.4</jats:sub>MnO<jats:sub>3</jats:sub>/<jats:italic>A</jats:italic>-type AF La<jats:sub>0.45</jats:sub>Sr<jats:sub>0.55</jats:sub>MnO<jats:sub>3</jats:sub> along the growth directions. Large magnetoresistance subsists down to low temperature in La<jats:sub>0.6</jats:sub>Sr<jats:sub>0.4</jats:sub>MnO<jats:sub>3</jats:sub>/La<jats:sub>0.6</jats:sub>Sr<jats:sub>0.4</jats:sub> Fe<jats:sub>3</jats:sub> (<jats:italic>F</jats:italic>/<jats:italic>G</jats:italic>) superlattices as a result of recovery of ferromagnetism, which is once suppressed by spin frustration at the interface between FM and <jats:italic>G</jats:italic>-type AF layers. In contrast, the constituent layers in the La<jats:sub>0.6</jats:sub>Sr<jats:sub>0.4</jats:sub>MnO<jats:sub>3</jats:sub>/La<jats:sub>0.45</jats:sub>Sr<jats:sub>0.55</jats:sub>MnO<jats:sub>3</jats:sub> (<jats:italic>F</jats:italic>/<jats:italic>A</jats:italic>) superlattices appear to keep their ground states due to the absence of spin frustration at the interface. Magnetoresistance is pronounced in this type of superlattices at low temperatures when the AF layer is very thin, indicating restoration of the electronic coupling between the neighboring FM layers which are otherwise decoupled by intervening <jats:italic>A</jats:italic>-type AF spin ordering and d<jats:sub><jats:italic>x</jats:italic><jats:sup>2</jats:sup>−<jats:italic>y</jats:italic><jats:sup>2</jats:sup></jats:sub> orbital ordering in La<jats:sub>0.45</jats:sub>Sr<jats:sub>0.55</jats:sub>MnO<jats:sub>3</jats:sub> layers.</jats:p>