Structural, Magnetic and Magnotransport Properties of Perovskite Superlattices

Francis Bern,

Division of Superconductivity and Magnetism, University of Leipzig, 04103 Leipzig, Germany

 

Good epitaxial growth characteristics make oxide heterostructures of the perovskite family a model system for the study of spatial confinement in ultrathin layers and emerging phenomena at interfaces. Here superlattices of La0.7Sr0.3MnO3, SrRuO3 and SrTiO3 with individual layer thicknesses between 2 and 20 unit cells were produced by pulsed laser deposition. Coherent growth was confirmed by XRD, AFM and HRTEM studies. Structurally, a phase transformation of the SrRuO3 as function of the La0.7Sr0.3MnO3 layer thickness is observed. The antiferromagnetic coupling between Ru and Mn layers and different magnetic anisotropies lead to a complex magnetization behaviour. This wide parameter space allows for tailoring of the magnetisation reversal mechanism. Although La0.7Sr0.3MnO3 of few unit cell thickness is known to be antiferromagnetic and insulating, ferromagnetism with a Curie temperature close to room temperature was observed in the superlattices. Whereas the resistivity of the samples is dominated by the „bad metal“ SrRuO3, the off-diagonal resistivity shows an anomalous Hall effect with a ferromagnetic loop shape even far above the Curie temperature of SrRuO3. This indicates the presence of an interfacial hole gas with an extension of only a few unit cell.

FECHA: Martes 6 de Noviembre

HORARIO: 10.30hs

LUGAR: Sala de Claustro (BLOCK 2, segundo piso)