Eur. Phys. J. B (2013) 86: 42
https://doi.org/10.1140/epjb/e2012-30646-4

Regular Article

Existence of a magnetically ordered hole gas at the La_0.7Sr_0.3MnO₃/SrRuO₃ interface^*

¹ Division of Superconductivity and Magnetism, University of Leipzig, Leipzig 04103, Germany
² Max Planck Institute of Microstructure Physics, Halle 06120, Germany
³ Max Planck Institute for Solid State Research, Stuttgart 70569, Germany

^a e-mail: ziese@physik.uni-leipzig.de

Received: 19 July 2012
Published online: 6 February 2013

Abstract

The study of spatially confined complex oxides is of wide interest, since correlated electrons at interfaces might form new states of matter. Here La_0.7Sr_0.3MnO₃/SrRuO₃ superlattices with coherently grown interfaces and layer thicknesses down to one unit cell were fabricated by pulsed laser deposition. The superlattices were studied by X-ray, HRTEM, magnetization and magnetotransport measurements. For such small thicknesses La_0.7Sr_0.3MnO₃ films are antiferromagnetic and insulating. Despite the small layer thickness, the LaSrMnO layers in the superlattices were ferromagnetic with Curie temperatures close to room temperature. Whereas the resistivity of the superlattices showed metallic behaviour and was dominated by the conducting SrRuO₃ layers, the off-diagonal resistivity showed an anomalous Hall effect with ferromagnetic loop shape even far above the Curie temperature of the SrRuO₃ layers as well as a positive high field slope. This indicates the presence of a highly conducting, ferromagnetically ordered hole gas at the interfaces that might be formed by a charge-transfer process. This result opens up an alternative route for the fabrication of quasi-two-dimensional systems.