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2012


Fourier-transform photocurrent spectroscopy using a supercontinuum light source
Fourier-transform photocurrent spectroscopy using a supercontinuum light source

Petermann, C., Beigang, R., Fischer, P.

APPLIED PHYSICS LETTERS, 100(6), 2012 (article)

Abstract
We demonstrate an implementation of frequency-encoded photocurrent spectroscopy using a super-continuum light source. The spectrally broad light is spatially dispersed and modulated with a special mechanical chopper design that permits a continuous wavelength-dependent modulation. After recombination, the light beam contains a frequency encoded spectrum which enables us to map the spectral response of a given sample in 60 ms and with a lateral resolution of 10 mu m. (C) 2012 American Institute of Physics.

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DOI [BibTex]

2012


DOI [BibTex]


Eine neue Form von Cavity Enhanced Absorption Spectroscopy
Eine neue Form von Cavity Enhanced Absorption Spectroscopy

Petermann, C., Fischer, P.

DE Gruyter, 79(1), 2012, Best paper award OPTO 2011 (article)

Abstract
Wir stellen eine Kopplungsmethode für resonatorgestützte Absorptionsmessungen vor, bei der Licht durch einen im Resonator platzierten akustooptischen Modulator aktiv ein- und ausgekoppelt wird. Dies ermöglicht es Cavity-Ring-Down-Spektroskopie (CRDS) mit breitbandigen und zeitlich inkohärenten Lichtquellen niedriger spektraler Leistungsdichte durchzuführen. Das Verfahren wird zum ersten Mal mit einer breitbandigen Superkontinuum-Quelle demonstriert.

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A new coupling scheme for cavity enhanced absorption spectroscopy makes use of an intracavity acousto-optical modulator to actively switch light into (and out of) a resonator. This allows cavity ringdown spectroscopy (CRDS) to be implemented with broadband temporally incoherent light sources with low spectral power densities. The method is demonstrated for the first time using a broadband supercontinuum source. Best paper award OPTO 2011.

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link (url) [BibTex]

link (url) [BibTex]


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Vortex dynamics in nonparabolic potentials

Langner, H. H., Kamionka, T., Martens, M., Weigand, M., Adolff, C. F., Merkt, U., Meier, G.

{Physical Review B}, 85(17), 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Micromagnetic simulations on GPU, a case study: Vortex core switcing by high-frequency magnetic fields

Van de Wiele, B, Vansteenkiste, A., Kammerer, M., Van Waeyenberge, B., Dupré, L., De Zutter, D.

{IEEE Transactions on Magnetics}, 48(6):2068-2072, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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On the energetics of transversal and longitudinal fluctuations of atomic magnetic moments

Dietermann, F., Sandratskii, L. M., Fähnle, M.

{Journal of Magnetism and Magnetic Materials}, 324(18):2693-2695, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Gradual softening of Al-Zn alloys during high-pressure torsion

Mazilkin, A. A., Straumal, B. B., Borodachenkova, M. V., Valiev, R. Z., Kogtenkova, O. A., Baretzky, B.

{Materials Letters}, 84, pages: 63-65, North-Holland, Amsterdam, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Direct imaging of phase relation in a pair of coupled vortex oscillators

Vogel, A., Drews, A., Weigand, M., Meier, G.

{AIP Advances}, 2, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Accurate dosimetry in scanning transmission X-ray microscopes via the cross-linking threshold dose of poly(methyl methacrylate)

Leontowich, A. F. G., Hitchcock, A. P., Tyliszczak, T., Weigand, M., Wang, J., Karunakaran, C.

{Journal of Synchrotron Radiation}, 19(6):976-987, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Biogenic potassium salt particles as seeds for secondary organic aerosal in the amazon

Pöhlker, C., Wiedemann, K. T., Sinha, B., Shiraiwa, M., Gunthe, S. S., Smith, M., Su, H., Artaxo, P., Chen, Q., Cheng, Y., Elbert, W., Gilles, M. K., Kilcoyne, A. L. D., Moffet, R. C., Weigand, M., Martin, S. T., Pöschl, U., Andreae, M. O.

{Science}, 337, pages: 1075-1078, 2012 (article)

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DOI [BibTex]


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Metal@COFs: Covalent organic frameworks as templates for Pd nanoparticles and hydrogen storage properties of Pd@COF-102 hybrid material

Kalidindi, S. B., Oh, H., Hirscher, M., Esken, D., Wiktor, C., Turner, S., Van Tendeloo, G., Fischer, R. A.

{Chemistry-a European Journal}, 18(35):10848-10856, VCH Verlagsgesellschaft, Weinheim, Germany, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Ion beam lithography for direct patterning of high accuracy large area X-ray elements in gold on membranes

Nadzeyka, A., Peto, L., Bauerdick, S., Mayer, M., Keskinbora, K., Grévent, C., Weigand, M., Hirscher, M., Schütz, G.

{Microelectronic Engineering}, 98, pages: 198-201, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Micro- and nanoscale fluid flow on chemical channels

Dörfler, Fabian, Rauscher, Markus, Koplik, Joel, Harting, Jens, Dietrich, S.

{Soft Matter}, 8(35):9221-9234, 2012 (article)

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link (url) DOI [BibTex]

link (url) DOI [BibTex]


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Novel characterization of the adsorption sites in large pore Metal-Organic Frameworks: Combination of X-ray powder diffraction and thermal desorption spectroscopy

Soleimani Dorcheh, A., Dinnebier, R. E., Kuc, A., Magdysyuk, O., Adams, F., Denysenko, D., Heine, T., Volkmer, D., Donner, W., Hirscher, M.

{Physical Chemistry Chemical Physics}, 14(37):12892-12897, 2012 (article)

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DOI [BibTex]


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Tunnel contacts for spin injection into silicon: The Si-Co interface with and without a MgO tunnel barrier - A study by high-resolution Rutherford backscattering

Dash, S. P., Goll, D., Kopold, P., Carstanjen, H. D.

{Advances in Materials Science and Engineering}, 2012, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Fast spin-wave-mediated magnetic vortex core reversal

Kammerer, M., Stoll, H., Noske, M., Sproll, M., Weigand, M., Illg, C., Woltersdorf, G., Fähnle, M., Back, C., Schütz, G.

{Physical Review B}, 86(13), 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Deformation-driven formation of equilibrium phases in the Cu-Ni alloys

Straumal, B. B., Protasova, S. G., Mazilkin, A. A., Rabkin, E., Goll, D., Schütz, G., Baretzky, B., Valiev, R. Z.

{Journal of Materials Science}, 47, pages: 360-367, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Nanosponges for hydrogen storage

Schlichtenmayer, M., Hirscher, M.

{Journal of Materials Chemistry}, 22, pages: 10134-10143, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Magnetic and electronic properties of the interface between half metallic Fe3O4 and semiconducting ZnO

Brück, S., Paul, M., Tian, H., Müller, A., Kufer, D., Praetorius, C., Fauth, K., Audehm, P., Goering, E., Verbeeck, J., Van Tendeloo, G., Sing, M., Claessen, R.

{Applied Physics Letters}, 100, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Amorphous interlayers between crystalline grains in ferromagnetic ZnO films

Straumal, B. B., Protasova, S. G., Mazilkin, A. A., Baretzky, B., Myatiev, A. A., Straumal, P. B., Tietze, T., Schütz, G., Goering, E.

{Materials Letters}, 71, pages: 21-24, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Accelerated diffusion and phase transformations in Co-Cu alloys driven by the severe plastic deformation

Straumal, B. B., Mazilkin, A. A., Baretzky, B., Schütz, G., Rabkin, E., Valiev, R. Z.

{Special Issue on Advanced Materials Science in Bulk Nanostructured Metals}, 53(1):63-71, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Unusual flux jumps above 12 K in non-homogeneous MgB2 thin films

Treiber, S., Stahl, C., Schütz, G., Albrecht, J.

{Superconductor Science \& Technology}, 25, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Ferromagnetism of nanostructured zinc oxide films

Straumal, B. B., Mazilkin, A. A., Protasova, S. G., Straumal, P. B., Myatiev, A. A., Schütz, G., Goering, E., Baretzky, B.

{The Physics of Metals and Metallography}, 113(13):1244-1256, 2012 (article)

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DOI [BibTex]


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Frequencies and polarization vectors of phonons: Results from force constants which are fitted to experimental data or calculated ab initio

Illg, C., Meyer, B., Fähnle, M.

{Physical Review B}, 86(17), Published by the American Physical Society through the American Institute of Physics, Woodbury, NY, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Grain boundary wetting by a second solid phase in the Zr-Nb alloys

Straumal, B. B., Gornakova, A. S., Kucheev, Y. O., Baretzky, B., Nekrasov, A. N.

{Journal of Materials Engineering and Performance}, 21(5):721-724, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Grain boundary wetting in the NdFeB-based hard magnetic alloys

Straumal, B. B., Kucheev, Y. O., Yatskovskaya, I. L., Mogilnikova, I. V., Schütz, G., Nekrasov, A. N., Baretzky, B.

{Journal of Materials Science}, 47(24):8352-8359, 2012 (article)

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DOI [BibTex]


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Magnetic proximity effect in YBa2Cu3O7 / La2/3Ca1/3MnO3 and YBa2Cu3O7 / LaMnO3+δsuperlattices

Satapathy, D. K., Uribe-Laverde, M. A., Marozau, I., Malik, V. K., Das, S., Wagner, T., Marcelot, C., Stahn, J., Brück, S., Rühm, A., Macke, S., Tietze, T., Goering, E., Frañó, A., Kim, J., Wu, M., Benckiser, E., Keimer, B., Devishvili, A., Toperverg, B. P., Merz, M., Nagel, P., Schuppler, S., Bernhard, C.

{Physical Review Letters}, 108, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Noble gases and microporous frameworks; from interaction to application

Soleimani Dorcheh, A., Denysenko, D., Volkmer, D., Donner, W., Hirscher, M.

{Microporous and Mesoporous Materials}, 162, pages: 64-68, Elsevier, Amsterdam, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Note: Unique characterization possibilities in the ultra high vacuum scanning transmission x-ray microscope (UHV-STXM) "MAXYMUS" using a rotatable permanent magnetic field up to 0.22 T

Nolle, D., Weigand, M., Audehm, P., Goering, E., Wiesemann, U., Wolter, C., Nolle, E., Schütz, G.

{Review of Scientific Instruments}, 83(4), 2012 (article)

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Microstructure and superconducting properties of MgB2 films prepared by solid state reaction of multilayer precursors of the elements

Kugler, B., Stahl, C., Treiber, S., Soltan, S., Haug, S., Schütz, G., Albrecht, J.

{Thin Solid Films}, 520, pages: 6985-6988, 2012 (article)

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DOI [BibTex]

DOI [BibTex]

2011


Quantum-Cascade Laser-Based Vibrational Circular Dichroism
Quantum-Cascade Laser-Based Vibrational Circular Dichroism

Luedeke, S., Pfeifer, M., Fischer, P.

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 133(15):5704-5707, 2011 (article)

Abstract
Vibrational circular dichroism (VCD) spectra were recorded with a tunable external-cavity quantum-cascade laser (QCL). In comparison with standard thermal light sources in the IR, QCLs provide orders of magnitude more power and are therefore promising for VCD studies in strongly absorbing solvents. The brightness of this novel light source is demonstrated with VCD and IR absorption measurements of a number of compounds, including proline in water.

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DOI [BibTex]

2011


DOI [BibTex]


Actively coupled cavity ringdown spectroscopy with low-power broadband sources
Actively coupled cavity ringdown spectroscopy with low-power broadband sources

Petermann, C., Fischer, P.

OPTICS EXPRESS, 19(11):10164-10173, 2011 (article)

Abstract
We demonstrate a coupling scheme for cavity enhanced absorption spectroscopy that makes use of an intracavity acousto-optical modulator to actively switch light into (and out of) a resonator. This allows cavity ringdown spectroscopy (CRDS) to be implemented with broadband nonlaser light sources with spectral power densities of less than 30 mu W/nm. Although the acousto-optical element reduces the ultimate detection limit by introducing additional losses, it permits absorptivities to be measured with a high dynamic range, especially in lossy environments. Absorption measurements for the forbidden transition of gaseous oxygen in air at similar to 760nm are presented using a low-coherence cw-superluminescent diode. The same setup was electronically configured to cover absorption losses from 1.8 x 10(-8)cm(-1) to 7.5\% per roundtrip. This could be of interest in process analytical applications. (C) 2011 Optical Society of America

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DOI [BibTex]

DOI [BibTex]


Magnetically actuated propulsion at low Reynolds numbers: towards nanoscale control
Magnetically actuated propulsion at low Reynolds numbers: towards nanoscale control

Fischer, P., Ghosh, A.

NANOSCALE, 3(2):557-563, 2011 (article)

Abstract
Significant progress has been made in the fabrication of micron and sub-micron structures whose motion can be controlled in liquids under ambient conditions. The aim of many of these engineering endeavors is to be able to build and propel an artificial micro-structure that rivals the versatility of biological swimmers of similar size, e. g. motile bacterial cells. Applications for such artificial ``micro-bots'' are envisioned to range from microrheology to targeted drug delivery and microsurgery, and require full motion-control under ambient conditions. In this Mini-Review we discuss the construction, actuation, and operation of several devices that have recently been reported, especially systems that can be controlled by and propelled with homogenous magnetic fields. We describe the fabrication and associated experimental challenges and discuss potential applications.

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Video - Nanospropellers DOI [BibTex]


The Oxidation of Fe(111)
The Oxidation of Fe(111)

Davies, R., Edwards, D., Gräfe, J., Gilbert, L., Davies, P., Hutchings, G., Bowker, M.

Surface Science, 605(17-18):1754-1762, 2011 (article)

Abstract
The oxidation of Fe(111) was studied using Auger electron spectroscopy (AES), low energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), ion scattering spectroscopy (ISS) and scanning tunnelling microscopy (STM). Oxidation of the crystal was found to be a very fast process, even at 200 K, and the Auger O signal saturation level is reached within ~ 50 × 10− 6 mbar s. Annealing the oxidised surface at 773 K causes a significant decline in apparent surface oxygen concentration and produces a clear (6 × 6) LEED pattern, whereas after oxidation at ambient temperature no pattern was observed. STM results indicate that the oxygen signal was reduced due to the nucleation of large, but sparsely distributed oxide islands, leaving mainly the smooth (6 × 6) structure between the islands. The reactivity of the (6 × 6) layer towards methanol was investigated using temperature programmed desorption (TPD), which showed mainly decomposition to CO and CO2, due to the production of formate intermediates on the surface. Interestingly, this removes the (6 × 6) structure by reduction, but it can be reformed from the sink of oxygen present in the large oxide islands simply by annealing at 773 K for a few minutes. The (6 × 6) appears to be a relatively stable, pseudo-oxide phase, that may be useful as a model oxide surface.

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DOI [BibTex]

DOI [BibTex]


Weak value amplified optical activity measurements
Weak value amplified optical activity measurements

Pfeifer, M., Fischer, P.

Opt. Express, 19(17):16508-16517, OSA, 2011 (article)

Abstract
We present a new form of optical activity measurement based on a modified weak value amplification scheme. It has recently been shown experimentally that the left- and right-circular polarization components refract with slightly different angles of refraction at a chiral interface causing a linearly polarized light beam to split into two. By introducing a polarization modulation that does not give rise to a change in the optical rotation it is possible to differentiate between the two circular polarization components even after post-selection with a linear polarizer. We show that such a modified weak value amplification measurement permits the sign of the splitting and thus the handedness of the optically active medium to be determined. Angular beam separations of Δθ ∼ 1 nanoradian, which corresponds to a circular birefringence of Δn ∼ 1 × 10−9, could be measured with a relative error of less than 1%.

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link (url) DOI [BibTex]

link (url) DOI [BibTex]


High-resolution x-ray absorption spectroscopy of BaTiO${}_{3}$: Experiment and first-principles calculations
High-resolution x-ray absorption spectroscopy of BaTiO_3: Experiment and first-principles calculations

Chassé, A., Borek, S., Schindler, K., Trautmann, M., Huth, M., Steudel, F., Makhova, L., Gräfe, J., Denecke, R.

Physical Review B, 84, pages: 195135, 2011 (article)

Abstract
High resolution x-ray absorption spectroscopy (XAS) affords new insight into the microscopic properties of perovskite transition metal oxides. Interpretation of XAS spectra in transition metal oxides requires theoretical tools capable of describing relativistic and many-body effects. In this work, full relativistic (SPR-KKR) and multiplet calculations (CTM4XAS) are carried out and compared to experimental multiedge XAS spectra of BaTiO3 single crystals. The impact of relativistic and many-body effects on the calculated density of states and x-ray absorption near edge structure spectra are individually considered.

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DOI [BibTex]

DOI [BibTex]


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Electron theory of fast and ultrafast dissipative magnetization dynamics

Fähnle, M., Illg, C.

{Journal of Physics: Condensed Matter}, 23, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Large-area hard magnetic L10-FePt nanopatterns by nanoimprint lithography

Bublat, T., Goll, D.

{Nanotechnology}, 22(31), 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Hydrogen storage by cryoadsorption in ultrahigh-porosity metal-organic frameworks

Hirscher, M.

{Angewandte Chemie International Edition}, 50(3):581-582, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Multilayer Fresnel zone plate for soft X-ray microscopy resolves sub-39 nm structures

Mayer, M., Grévent, C., Szeghalmi, A., Knez, M., Weigand, M., Rehbein, S., Schneider, G., Baretzky, B., Schütz, G.

{Ultramicroscopy}, 111, pages: 1706-1711, 2011 (article)

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DOI [BibTex]


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Generalized Gilbert equation including inertial damping: derivation from an extended breathing Fermi surface model

Fähnle, M., Steiauf, D., Illg, C.

{Physical Review B}, 84, 2011 (article)

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DOI [BibTex]


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Hydrogen physisorption in high SSA microporous materials - A comparison between AX-21\textunderscore33 and MOF-177 at cryogenic conditions

Schlichtenmayer, M., Streppel, B., Hirscher, M.

{International Journal of Hydrogen Energy}, 36, pages: 586-591, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Magnetic vortex core reversal by excitation of spin waves

Kammerer, M., Weigand, M., Curcic, M., Noske, M., Sproll, M., Vansteenkiste, A., Van Waeyenberge, B., Stoll, H., Woltersdorf, G., Back, C. H., Schütz, G.

{Nature Communications}, 2, pages: 279-284, 2011 (article)

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DOI [BibTex]


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Magnetism studied with circularly polarized X-rays

Schütz, G., Goering, E., Stoll, H.

{International Journal of Materials Research}, 102(7):773-783, 2011 (article)

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DOI [BibTex]


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Coupled vortex oscillations in spatially separated permalloy squares

Vogel, A., Kamionka, T., Martens, M., Drews, A., Chou, K., Tyliszczak, T., Stoll, H., Van Waeyenberge, B., Meier, G.

{Physical Review Letters}, 106, 2011 (article)

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DOI [BibTex]


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Contruction of basis functions with crystal symmetry for the spin-cluster expansion of the magnetic energy on the atomic scale

Dietermann, F., Singer, R., Fähnle, M.

{Journal of Mathematical Physics}, 52, 2011 (article)

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DOI [BibTex]


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Magnetic patterning perpendicular anisotropy FePd alloy films by masked ion irradiation

Merkel, D. G., Bottyán, L., Tanczikó, F., Zolnai, Z., Nagy, N., Vértesy, G., Waizinger, J., Bommer, L.

{Journal of Applied Physics}, 109(12), 2011 (article)

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DOI [BibTex]


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Characterization of hydrogen/deuterium adsorption sites in nanoporous Cu-BTC by low-temperature thermal-desorption mass spectroscopy

Krkljus, I., Hirscher, M.

{Microporous and Mesoporous Materials}, 142, pages: 725-729, 2011 (article)

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Stability of the current-carrying state in nonhomogeneous MgB2 films

Treiber, S., Stahl, C., Schütz, G., Albrecht, J.

{Physical Review B}, 84, 2011 (article)

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DOI [BibTex]

DOI [BibTex]