Critical thickness and orbital ordering in ultrathinLa0.7Sr0.3MnO3films

Abstract

Detailed analysis of transport, magnetism, and x-ray absorption spectroscopy measurements on ultrathin La 0.7 Sr 0.3 MnO 3 films with thicknesses from 3 to 70 unit cells resulted in the identification of a lower critical thickness for a nonmetallic nonferromagnetic layer at the interface with the SrTiO 3 ͑001͒ substrate of only three unit cells ͑ϳ12 Å͒. Furthermore, linear-dichroism measurements demonstrate the presence of a preferred ͑x 2 -y 2 ͒ in-plane orbital ordering for all layer thicknesses without any orbital reconstruction at the interface. A crucial requirement for the accurate study of these ultrathin films is a controlled growth process, offering the coexistence of layer-by-layer growth and bulklike magnetic/transport properties.

Reversible Modulation of Orbital Occupations via an Interface-Induced Polar State in Metallic Manganites

“…Tensile (compressive) strain modifies the crystal field so as to favor the in-plane orbital d x 2 −y 2 (out-of-plane orbital d 3z 2 −r 2 ). 9,10 However, utilizing strain is a static approach to tailoring the desired orbital configuration. 21 In this Letter, we describe an approach that utilizes nanoscale ferroelectrics and enables reversibly modulating orbital occupations at La 1−x Sr x MnO 3 (LSMO, x=0.2 for the current study) interfaces.…”

Visualizing the interfacial evolution from charge compensation to metallic screening across the manganite metal–insulator transition

“…11). Observed interfacial dead layers have, however, limited the scaling of potential devices [12][13][14] . While explicit attempts 15,16 to offset the interface dipole 17,18 and to eliminate extrinsic defects 14 have reduced the observed dead layer thickness, direct mapping of these intrinsic electronic and magnetic reconstructions at the interface can be obscured by variations in growth techniques leading to competing defects.…”

Interfaces and Nanostructures of Functional Oxide Octahedral Framework Structures

“…In the La 1-x Sr x MnO 3 solid solution, the electron occupancy of the e g doublet depends on the strength of the JahnTeller distortion, which in turn is determined by the hole doping level, x (Tokura and Nagaosa, 2000). In epitaxial thin films, however, similarly to the Jahn-Teller distortion, misfit strains have the ability to break the x 2 − y 2 /3z 2 − r 2 orbital degeneracy (Fang et al, 2000) as recently confirmed by X-ray linear dichroism investigations (Huijben et al, 2008;Tebano et al, 2008;Pesquera et al, 2012). A thorough investigation taking into account the attenuation of the signal with the depth in the sample, suggests that the observed X-ray linear dichroism is rather a consequence of the superposition of interfacial and free surface effects (Pesquera et al, 2012).…”