Document VersionEarly version, also known as pre-print Link back to DTU Orbit Citation (APA):Chen, Y., Trier, F., Wijnands, T., Green, R. J., Gauquelin, N., Egoavil, R., ... Pryds, N. (2015). Extreme mobility enhancement of two-dimensional electron gases at oxide interfaces via charge transfer induced modulation doping. Nature Materials, 14(8) Supplementary Information, Fig. S1). For all samples, with the d-LAO film thickness up to 20 nm, atomic force microscopy (AFM) images show regular surface terraces with a step height of 0.4 nm (Fig. 1b), similar to that of the original STO substrate and indicating uniform film growth. Representative samples were investigated further by scanning transmission electron microscopy (STEM). Our subsequent spectroscopic measurements reveal dramatic electronic reconstruction in the LSMO-buffered samples. Firstly, different from the unbuffered d-LAO/STO sample where the 2DEG is coupled strongly to a large content of oxygen vacancies extending more than 3 nm deep into STO 24 , all buffered samples show a rather low content of Ti 3+ far below the detection limit of our in situ X-ray photoelectron

A facile urea-assisted hydrothermal synthesis and systematic characterization of hydroxyapatite (HA) with calcium nitrate tetrahydrate and diammonium hydrogen phosphate as precursors are reported. The advantage of the proposed technique over previously reported synthetic approaches is the simple but precise control of the HA crystals morphology, which is achieved by employing an intensive, stepwise, and slow thermal decomposition of urea as well as varying initial concentrations of starting reagents. Whereas the plate-, hexagonal prism- and needle-like HA particles preferentially growth along the c-axis, the smaller and fine-plate-like HA crystals demonstrate crystal growth along the (102) and (211) directions, uncommon for HA. Furthermore, it was established that the hydrothermally derived powdered products are phase-pure HA containing CO3 2− anions in the crystal lattice, that is, AB-type carbonated hydroxyapatite. Transmission electron microscopy (TEM) and electron diffraction (ED) of selected samples reveal that the as-prepared HA crystals are single-crystalline and exhibit a nearly defect-free microstructure. The hardness and elastic modulus of the hexagonal prism-like HA crystals have been investigated on a nanoscale using the nanoindentation technique; the observed trends are discussed.

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Supplementary Information: DOI 10.1002/adfm.201102763, Preventing the reconstruction of the polar discontinuity at oxide heterointerfaces Determination of the Curie temperature When comparing a set of La 0.67 Sr 0.33 MnO 3 (LSMO) samples, the Curie temperature (T C ) of the samples is an important figure of merit for the sample quality. Therefore, a reliable method to determine T C is required. Here, a method based on the analysis of the magnetization loops is proposed. Magnetization measurementsT C is the temperature above, which the spontaneous magnetization disappears. However, the magnetic signal of LSMO does not drop to zero at T C in most measurements, as typically a small background field is used. This background field is necessary as LSMO's magnetization is very weak with a coercivity, which approaches zero around T C . LSMO's spontaneous magnetization will therefore be divided into domains with different orientations and no net magnetization can be observed without the background field. Above T C , LSMO has a very

Determining the three-dimensional (3D) arrangement of atoms in crystalline nanoparticles is important for nanometre-scale device engineering and also for applications involving nanoparticles, such as optoelectronics or catalysis. A nanoparticle's physical and chemical properties are controlled by its exact 3D morphology, structure and composition 1 . Electron tomography enables the recovery of the shape of a nanoparticle from a series of projection images [2][3][4] . Although atomic-resolution electron microscopy has been feasible for nearly four decades, neither electron tomography nor any other experimental technique has yet demonstrated atomic resolution in three dimensions. Here we report the 3D reconstruction of a complex crystalline nanoparticle at atomic resolution. To achieve this, we combined aberration-corrected scanning transmission electron microscopy [5][6][7] , statistical parameter estimation theory 8,9 and discrete tomography 10,11 . Unlike conventional electron tomography, only two images of the target-a silver nanoparticle embedded in an aluminium matrix-are sufficient for the reconstruction when combined with available knowledge about the particle's crystallographic structure. Additional projections confirm the reliability of the result. The results we present help close the gap between the atomic resolution achievable in two-dimensional electron micrographs and the coarser resolution that has hitherto been obtained by conventional electron tomography.High-angle annular dark field scanning transmission electron microscopy (HAADF STEM) is an imaging technique in which a focused electron probe is scanned across an electron-transparent sample 12 .Using an annular-shaped high-angle detector behind the sample, the signal is dominated by Rutherford and thermal diffuse scattering. When applied to a nanocrystal in zone-axis orientation, the HAADF signal approximately scales with the square of the atomic number Z and with the thickness of the sample [13][14][15] . By using aberration-corrected probe forming optics [5][6][7] , a resolution of the order of 50 picometres can nowadays be demonstrated 16 . Therefore, it is generally believed that aberration-corrected HAADF STEM has the potential to achieve atomic resolution in three dimensions. Electron tomography is the most common approach used to reconstruct nanomaterials in three dimensions. The 3D reconstruction is computed from a tilt series of projection images acquired while rotating the sample. Spatial resolution for the reconstruction is around one cubic nanometre 2-4 , limiting its use for attaining atomic resolution. Another potential technique with which to obtain 3D structure information is 'depth-sectioning', in which a sample is optically sliced by changing the objective lens focus 17 . Single atoms can be visualized using this technique 18 , yet 3D reconstructions at atomic resolution have not been demonstrated because the depth resolution is insufficient to resolve interatomic distances along the optical axis. Discrete tomography, a recons...