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2020


Characterization of active matter in dense suspensions with heterodyne laser Doppler velocimetry
Characterization of active matter in dense suspensions with heterodyne laser Doppler velocimetry

Sachs, J., Kottapalli, S. N., Fischer, P., Botin, D., Palberg, T.

Colloid and Polymer Science, August 2020 (article)

Abstract
We present a novel approach for characterizing the properties and performance of active matter in dilute suspension as well as in crowded environments. We use Super-Heterodyne Laser-Doppler-Velocimetry (SH-LDV) to study large ensembles of catalytically active Janus particles moving under UV illumination. SH-LDV facilitates a model-free determination of the swimming speed and direction, with excellent ensemble averaging. In addition, we obtain information on the distribution of the catalytic activity. Moreover, SH-LDV operates away from walls and permits a facile correction for multiple scattering contributions. It thus allows for studies of concentrated suspensions of swimmers or of systems where swimmers propel actively in an environment crowded by passive particles. We demonstrate the versatility and the scope of the method with a few selected examples. We anticipate that SH-LDV complements established methods and paves the way for systematic measurements at previously inaccessible boundary conditions.

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link (url) DOI [BibTex]

2020


link (url) DOI [BibTex]


Biocompatible magnetic micro‐ and nanodevices: Fabrication of FePt nanopropellers and cell transfection
Biocompatible magnetic micro‐ and nanodevices: Fabrication of FePt nanopropellers and cell transfection

Kadiri, V. M., Bussi, C., Holle, A. W., Son, K., Kwon, H., Schütz, G., Gutierrez, M. G., Fischer, P.

Adv. Mat., 32(2001114), May 2020 (article)

Abstract
The application of nanoparticles for drug or gene delivery promises benefits in the form of single‐cell‐specific therapeutic and diagnostic capabilities. Many methods of cell transfection rely on unspecific means to increase the transport of genetic material into cells. Targeted transport is in principle possible with magnetically propelled micromotors, which allow responsive nanoscale actuation and delivery. However, many commonly used magnetic materials (e.g., Ni and Co) are not biocompatible, possess weak magnetic remanence (Fe3O4), or cannot be implemented in nanofabrication schemes (NdFeB). Here, it is demonstrated that co‐depositing iron (Fe) and platinum (Pt) followed by one single annealing step, without the need for solution processing, yields ferromagnetic FePt nanomotors that are noncytotoxic, biocompatible, and possess a remanence and magnetization that rival those of permanent NdFeB micromagnets. Active cell targeting and magnetic transfection of lung carcinoma cells are demonstrated using gradient‐free rotating millitesla fields to drive the FePt nanopropellers. The carcinoma cells express enhanced green fluorescent protein after internalization and cell viability is unaffected by the presence of the FePt nanopropellers. The results establish FePt, prepared in the L10 phase, as a promising magnetic material for biomedical applications with superior magnetic performance, especially for micro‐ and nanodevices.

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link (url) DOI [BibTex]


Interface-mediated spontaneous symmetry breaking and mutual communication between drops containing chemically active particles
Interface-mediated spontaneous symmetry breaking and mutual communication between drops containing chemically active particles

Singh, D., Domínguez, A., Choudhury, U., Kottapalli, S., Popescu, M., Dietrich, S., Fischer, P.

Nature Communications, 11(2210), May 2020 (article)

Abstract
Symmetry breaking and the emergence of self-organized patterns is the hallmark of com- plexity. Here, we demonstrate that a sessile drop, containing titania powder particles with negligible self-propulsion, exhibits a transition to collective motion leading to self-organized flow patterns. This phenomenology emerges through a novel mechanism involving the interplay between the chemical activity of the photocatalytic particles, which induces Mar- angoni stresses at the liquid–liquid interface, and the geometrical confinement provided by the drop. The response of the interface to the chemical activity of the particles is the source of a significantly amplified hydrodynamic flow within the drop, which moves the particles. Furthermore, in ensembles of such active drops long-ranged ordering of the flow patterns within the drops is observed. We show that the ordering is dictated by a chemical com- munication between drops, i.e., an alignment of the flow patterns is induced by the gradients of the chemicals emanating from the active particles, rather than by hydrodynamic interactions.

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link (url) DOI [BibTex]


Spectrally selective and highly-sensitive UV photodetection with UV-A, C band specific polarity switching in silver plasmonic nanoparticle enhanced gallium oxide thin-film
Spectrally selective and highly-sensitive UV photodetection with UV-A, C band specific polarity switching in silver plasmonic nanoparticle enhanced gallium oxide thin-film

Arora, K., Singh, D., Fischer, P., Kumar, M.

Adv. Opt. Mat., March 2020 (article)

Abstract
Traditional photodetectors generally show a unipolar photocurrent response when illuminated with light of wavelength equal or shorter than the optical bandgap. Here, we report that a thin film of gallium oxide (GO) decorated with plasmonic nanoparticles, surprisingly, exhibits a change in the polarity of the photocurrent for different UV bands. Silver (Ag) nanoparticles are vacuum-deposited onto β-Ga2O3 and the AgNP@GO thin films show a record responsivity of 250 A/W, which significantly outperforms bare GO planar photodetectors. The photoresponsivity reverses sign from +157 µA/W in the UV-C band under unbiased operation to -353 µA/W in the UV-A band. The current reversal is rationalized by considering the charge dynamics stemming from hot electrons generated when the incident light excites a local surface plasmon resonance (LSPR) in the Ag nanoparticles. The Ag nanoparticles improve the external quantum efficiency and detectivity by nearly one order of magnitude with high values of 1.2×105 and 3.4×1014 Jones, respectively. This plasmon-enhanced solar blind GO detector allows UV regions to be spectrally distinguished, which is useful for the development of sensitive dynamic imaging photodetectors.

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link (url) DOI [BibTex]


Investigating photoresponsivity of graphene-silver hybrid nanomaterials in the ultraviolet
Investigating photoresponsivity of graphene-silver hybrid nanomaterials in the ultraviolet

Deshpande, P., Suri, P., Jeong, H., Fischer, P., Ghosh, A., Ghosh, G.

J. Chem. Phys., 152, pages: 044709, January 2020 (article)

Abstract
There have been several reports of plasmonically enhanced graphene photodetectors in the visible and the near infrared regime but rarely in the ultraviolet. In a previous work, we have reported that a graphene-silver hybrid structure shows a high photoresponsivity of 13 A/W at 270 nm. Here, we consider the likely mechanisms that underlie this strong photoresponse. We investigate the role of the plasmonic layer and examine the response using silver and gold nanoparticles of similar dimensions and spatial arrangement. The effect on local doping, strain, and absorption properties of the hybrid is also probed by photocurrent measurements and Raman and UV-visible spectroscopy. We find that the local doping from the silver nanoparticles is stronger than that from gold and correlates with a measured photosensitivity that is larger in devices with a higher contact area between the plasmonic nanomaterials and the graphene layer.

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link (url) DOI [BibTex]

link (url) DOI [BibTex]


A High-Fidelity Phantom for the Simulation and Quantitative Evaluation of Transurethral Resection of the Prostate
A High-Fidelity Phantom for the Simulation and Quantitative Evaluation of Transurethral Resection of the Prostate

Choi, E., Adams, F., Gengenbacher, A., Schlager, D., Palagi, S., Müller, P., Wetterauer, U., Miernik, A., Fischer, P., Qiu, T.

Annals of Biomed. Eng., 48, pages: 437-446, January 2020 (article)

Abstract
Transurethral resection of the prostate (TURP) is a minimally invasive endoscopic procedure that requires experience and skill of the surgeon. To permit surgical training under realistic conditions we report a novel phantom of the human prostate that can be resected with TURP. The phantom mirrors the anatomy and haptic properties of the gland and permits quantitative evaluation of important surgical performance indicators. Mixtures of soft materials are engineered to mimic the physical properties of the human tissue, including the mechanical strength, the electrical and thermal conductivity, and the appearance under an endoscope. Electrocautery resection of the phantom closely resembles the procedure on human tissue. Ultrasound contrast agent was applied to the central zone, which was not detectable by the surgeon during the surgery but showed high contrast when imaged after the surgery, to serve as a label for the quantitative evaluation of the surgery. Quantitative criteria for performance assessment are established and evaluated by automated image analysis. We present the workflow of a surgical simulation on a prostate phantom followed by quantitative evaluation of the surgical performance. Surgery on the phantom is useful for medical training, and enables the development and testing of endoscopic and minimally invasive surgical instruments.

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link (url) DOI [BibTex]

link (url) DOI [BibTex]


Interactive Materials – Drivers of Future Robotic Systems
Interactive Materials – Drivers of Future Robotic Systems

Fischer, P.

Adv. Mat., January 2020 (article)

Abstract
A robot senses its environment, processes the sensory information, acts in response to these inputs, and possibly communicates with the outside world. Robots generally achieve these tasks with electronics-based hardware or by receiving inputs from some external hardware. In contrast, simple microorganisms can autonomously perceive, act, and communicate via purely physicochemical processes in soft material systems. A key property of biological systems is that they are built from energy-consuming ‘active’ units. Exciting developments in material science show that even very simple artificial active building blocks can show surprisingly rich emergent behaviors. Active non-equilibrium systems are therefore predicted to play an essential role to realize interactive materials. A major challenge is to find robust ways to couple and integrate the energy-consuming building blocks to the mechanical structure of the material. However, success in this endeavor will lead to a new generation of sophisticated micro- and soft-robotic systems that can operate autonomously.

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link (url) DOI [BibTex]


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Effect of the soft layer thickness of magnetization reversal process of exchange-spring nanomagnet patterns

Son, K., Schütz, G., Goering, E.

{Current Applied Physics}, 20(4):477-483, Elsevier B.V., Amsterdam, 2020 (article)

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DOI [BibTex]


{Creating zero-field skyrmions in exchange-biased multilayers through X-ray illumination}
Creating zero-field skyrmions in exchange-biased multilayers through X-ray illumination

Guang, Y., Bykova, I., Liu, Y., Yu, G., Goering, E., Weigand, M., Gräfe, J., Kim, S. K., Zhang, J., Zhang, H., Yan, Z., Wan, C., Feng, J., Wang, X., Guo, C., Wei, H., Peng, Y., Tserkovnyak, Y., Han, X., Schütz, G.

{Nature Communications}, 11, Nature Publishing Group, London, 2020 (article)

Abstract
Skyrmions, magnetic textures with topological stability, hold promises for high-density and energy-efficient information storage devices owing to their small size and low driving-current density. Precise creation of a single nanoscale skyrmion is a prerequisite to further understand the skyrmion physics and tailor skyrmion-based applications. Here, we demonstrate the creation of individual skyrmions at zero-field in an exchange-biased magnetic multilayer with exposure to soft X-rays. In particular, a single skyrmion with 100-nm size can be created at the desired position using a focused X-ray spot of sub-50-nm size. This single skyrmion creation is driven by the X-ray-induced modification of the antiferromagnetic order and the corresponding exchange bias. Furthermore, artificial skyrmion lattices with various arrangements can be patterned using X-ray. These results demonstrate the potential of accurate optical control of single skyrmion at sub-100 nm scale. We envision that X-ray could serve as a versatile tool for local manipulation of magnetic orders.

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DOI [BibTex]

DOI [BibTex]


{Tuning the magnetic properties of permalloy-based magnetoplasmonic crystals for sensor applications}
Tuning the magnetic properties of permalloy-based magnetoplasmonic crystals for sensor applications

Murzin, D. V., Belyaev, V. K., Groß, F., Gräfe, J., Rivas, M., Rodionova, V. V.

{Japanese Journal of Applied Physics}, 59(SE), IOP Publishing Ltd, Bristol, England, 2020 (article)

Abstract
Miniature magnetic sensors based on magnetoplasmonic crystals (MPlCs) exhibit high sensitivity and high spatial resolution, which can be obtained by the excitation of surface plasmon polaritons. A field dependence of surface plasmon polaritons' enhanced magneto-optical response strongly correlates with magnetic properties of MPlCs that can be tuned by changing spatial parameters, such as the period and height of diffraction gratings and thicknesses of functional layers. This work compares the magnetic properties of MPlCs based on Ni80Fe20 (permalloy) obtained from local (longitudinal magneto-optical Kerr effect) and bulk (vibrating-sample magnetometry) measurements and demonstrates an ability to control sensors' performance through changing the magnetic properties of the MPlCs. The influence of the substrate's geometry (planar or sinusoidal and trapezoidal diffraction grating profiles) and the thickness of the surface layer is examined.

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DOI [BibTex]

DOI [BibTex]


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Element-resolved study of the evolution of magnetic response in FexN compounds

Chen, Y., Gölden, D., Dirba, I., Huang, M., Gutfleisch, O., Nagel, P., Merz, M., Schuppler, S., Schütz, G., Alff, L., Goering, E.

{Journal of Magnetism and Magnetic Materials}, 498, NH, Elsevier, Amsterdam, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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The role of temperature and drive current in skyrmion dynamics

Litzius, K., Leliaert, J., Bassirian, P., Rodrigues, D., Kromin, S., Lemesh, I., Zazvorka, J., Lee, K., Mulkers, J., Kerber, N., Heinze, D., Keil, N., Reeve, R. M., Weigand, M., Van Waeyenberge, B., Schütz, G., Everschor-Sitte, K., Beach, G. S. D., Kläui, M.

{Nature Electronics}, 3(1):30-36, Springer Nature, London, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Magnetic flux penetration into micron-sized superconductor/ferromagnet bilayers

Simmendinger, J., Weigand, M., Schütz, G., Albrecht, J.

{Superconductor Science and Technology}, 33(2), IOP Pub., Bristol, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Fabrication and temperature-dependent magnetic properties of large-area L10-FePt/Co exchange-spring magnet nanopatterns

Son, K., Schütz, G.

{Physica E: Low-Dimensional Systems And Nanostructures}, 115, North-Holland, Amsterdam, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Research trend of metal-organic frameworks for magnetic refrigeration materials application

Kim, S., Son, K., Oh, H.

Korean Journal of Materials Research, 30(3):136-141, Materials Society of Korea, Seoul, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


Magnetic Anisotropy in Thin Layers of (Mn,Zn)Fe2O4 on SrTiO3 (001)
Magnetic Anisotropy in Thin Layers of (Mn,Zn)Fe2O4 on SrTiO3 (001)

Denecke, R., Welke, M., Huth, P., Gräfe, J., Brachwitz, K., Lorenz, M., Grundmann, M., Ziese, M., Esquinazi, P. D., Goering, E., Schütz, G., Schindler, K., Chassé, A.

Physica Status Solidi (b), 257(7):1900627, 2020 (article)

Abstract
Herein, a ferrimagnetic manganese zinc ferrite (Mn0.5Zn0.5Fe2O4) film with a thickness of 200 nm is prepared without a buffer layer on strontium titanate (001) (SrTiO3) using pulsed laser deposition. Its magnetic properties are investigated using superconducting quantum interference device (SQUID), X-ray absorption spectroscopy with subsequent X-ray magnetic circular dichroism (XMCD) and magneto-optic Kerr effect (MOKE). Hysteresis loops derived from SQUID exhibits bulk-like properties. This can further be confirmed by bulk-like XMCD spectra. In remanent magnetization, an in-plane magnetization with basically no out-of-plane component is found. The magnetic moments derived by the sum rule formalism from the XMCD data are in good agreement to the magnetization observed by SQUID and MOKE. XMCD as well as MOKE reveal an in-plane angular fourfold magnetic anisotropy with the easy direction along [110] for (Mn0.5Zn0.5)Fe2O4 on SrTiO3. The element-specific magnetic moments from XMCD show a stronger contribution of Fe to the anisotropy than of Mn and distinct contributions of the orbital moments.

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link (url) DOI [BibTex]

link (url) DOI [BibTex]


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How to functionalise metal-organic frameworks to enable guest nanocluster embedment

King, J., Zhang, L., Doszczeczko, S., Sambalova, O., Luo, H., Rohman, F., Phillips, O., Borgschulte, A., Hirscher, M., Addicoat, M., Szilágyi, P. A.

{Journal of Materials Chemistry A}, 8(9):4889-4897, Royal Society of Chemistry, Cambridge, UK, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Magnetic and microstructural properties of anisotropic MnBi magnets compacted by spark plasma sintering

Chen, Y., Gregori, G., Rheingans, B., Huang, W., Kronmüller, H., Schütz, G., Goering, E.

{Journal of Alloys and Compounds}, 830, Elsevier B.V., Lausanne, Switzerland, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Biocompatible magnetic micro- and nanodevices: Fabrication of FePt nanopropellers and cell transfection

Kadiri, V. M., Bussi, C., Holle, A. W., Son, K., Kwon, H., Schütz, G., Gutierrez, M. G., Fischer, P.

Advanced Materials, 32(25), Wiley-VCH, Weinheim, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Generation and characterization of focused helical x-ray beams

Loetgering, L., Baluktsian, M., Keskinbora, K., Horstmeyer, R., Wilhein, T., Schütz, G., Eikema, K. S. E., Witte, S.

Science Advances, 6(7), American Association for the Advancement of Science, 2020 (article)

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Generation and characterization of focused helical x-ray beams link (url) DOI [BibTex]

Generation and characterization of focused helical x-ray beams link (url) DOI [BibTex]


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Materials for hydrogen-based energy storage - past, recent progress and future outlook

Hirscher, M., Yartys, V. A., Baricco, M., Bellosta von Colbe, J., Blanchard, D., Bowman Jr., R. C., Broom, D. P., Buckley, C. E., Chang, F., Chen, P., Cho, Y. W., Crivello, J., Cuevas, F., David, W. I. F., de Jongh, P. E., Denys, R. V., Dornheim, M., Felderhoff, M., Filinchuk, Y., Froudakis, G. E., Grant, D. M., Gray, E. M., Hauback, B. C., He, T., Humphries, T. D., Jensen, T. R., Kim, S., Kojima, Y., Latroche, M., Li, H., Lotostskyy, M. V., Makepeace, J. W., M\oller, K. T., Naheed, L., Ngene, P., Noréus, D., Nyg\aard, M. M., Orimo, S., Paskevicius, M., Pasquini, L., Ravnsbaek, D. B., Sofianos, M. V., Udovic, T. J., Vegge, T., Walker, G. S., Webb, C. J., Weidenthaler, C., Zlotea, C.

{Journal of Alloys and Compounds}, 827, Elsevier B.V., Lausanne, Switzerland, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


{Thermal nucleation and high-resolution imaging of submicrometer magnetic bubbles in thin thulium iron garnet films with perpendicular anisotropy}
Thermal nucleation and high-resolution imaging of submicrometer magnetic bubbles in thin thulium iron garnet films with perpendicular anisotropy

Büttner, F., Mawass, M. A., Bauer, J., Rosenberg, E., Caretta, L., Avci, C. O., Gräfe, J., Finizio, S., Vaz, C. A. F., Novakovic, N., Weigand, M., Litzius, K., Förster, J., Träger, N., Groß, F., Suzuki, D., Huang, M., Bartell, J., Kronast, F., Raabe, J., Schütz, G., Ross, C. A., Beach, G. S. D.

{Physical Review Materials}, 4(1), American Physical Society, College Park, MD, 2020 (article)

Abstract
Ferrimagnetic iron garnets are promising materials for spintronics applications, characterized by ultralow damping and zero current shunting. It has recently been found that few nm-thick garnet films interfaced with a heavy metal can also exhibit sizable interfacial spin-orbit interactions, leading to the emergence, and efficient electrical control, of one-dimensional chiral domain walls. Two-dimensional bubbles, by contrast, have so far only been confirmed in micrometer-thick films. Here, we show by high resolution scanning transmission x-ray microscopy and photoemission electron microscopy that submicrometer bubbles can be nucleated and stabilized in ∼25-nm-thick thulium iron garnet films via short heat pulses generated by electric current in an adjacent Pt strip, or by ultrafast laser illumination. We also find that quasistatic processes do not lead to the formation of a bubble state, suggesting that the thermodynamic path to reaching that state requires transient dynamics. X-ray imaging reveals that the bubbles have Bloch-type walls with random chirality and topology, indicating negligible chiral interactions at the garnet film thickness studied here. The robustness of thermal nucleation and the feasibility demonstrated here to image garnet-based devices by x-rays both in transmission geometry and with sensitivity to the domain wall chirality are critical steps to enabling the study of small spin textures and dynamics in perpendicularly magnetized thin-film garnets.

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DOI [BibTex]

DOI [BibTex]


{Real-space imaging of confined magnetic skyrmion tubes}
Real-space imaging of confined magnetic skyrmion tubes

Birch, M. T., Cortés-Ortuño, D., Turnbull, L. A., Wilson, M. N., Groß, F., Träger, N., Laurenson, A., Bukin, N., Moody, S. H., Weigand, M., Schütz, G., Popescu, H., Fan, R., Steadman, P., Verezhak, J. A. T., Balakrishnan, G., Loudon, J. C., Twitchett-Harrison, A. C., Hovorka, O., Fangohr, H., Ogrin, F., Gräfe, J., Hatton, P. D.

Nature Communications, 11, pages: 1726, 2020 (article)

Abstract
Magnetic skyrmions are topologically nontrivial particles with a potential application as information elements in future spintronic device architectures. While they are commonly portrayed as two dimensional objects, in reality magnetic skyrmions are thought to exist as elongated, tube-like objects extending through the thickness of the host material. The study of this skyrmion tube state (SkT) is vital for furthering the understanding of skyrmion formation and dynamics for future applications. However, direct experimental imaging of skyrmion tubes has yet to be reported. Here, we demonstrate the real-space observation of skyrmion tubes in a lamella of FeGe using resonant magnetic x-ray imaging and comparative micromagnetic simulations, confirming their extended structure. The formation of these structures at the edge of the sample highlights the importance of confinement and edge effects in the stabilisation of the SkT state, opening the door to further investigation into this unexplored dimension of the skyrmion spin texture.

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link (url) DOI [BibTex]

link (url) DOI [BibTex]


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Current-induced dynamical tilting of chiral domain walls in curved microwires

Finizio, S., Wintz, S., Mayr, S., Huxtable, A. J., Langer, M., Bailey, J., Burnell, G., Marrows, C. H., Raabe, J.

Applied Physics Letters, 116(18), American Institute of Physics, Melville, NY, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Highly effective hydrogen isotope separation through dihydrogen bond on Cu(I)-exchanged zeolites well above liquid nitrogen temperature

Xiong, R., Zhang, L., Li, P., Luo, W., Tang, T., Ao, B., Sang, G., Chen, C., Yan, X., Chen, J., Hirscher, M.

Chemical Engineering Journal, 391, Elsevier, Lausanne, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Room temperature ferromagnetism driven by Ca-doped BiFeO3 multiferroic functional material

Marzouk, M., Hashem, H. M., Soltan, S., Ramadan, A. A.

{Journal of Materials Science: Materials in Electronics}, 31(7):5599-5607, Springer, Norwell, MA, 2020 (article)

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DOI [BibTex]

DOI [BibTex]

2001


Isotropic second-order nonlinear optical susceptibilities
Isotropic second-order nonlinear optical susceptibilities

Fischer, P., Buckingham, A., Albrecht, A.

PHYSICAL REVIEW A, 64(5), 2001 (article)

Abstract
The second-order nonlinear optical susceptibility, in the electric dipole approximation, is only nonvanishing for materials that are noncentrosymmetric. Should the medium be isotropic, then only a chiral system. such as an optically active liquid, satisfies this symmetry requirement. We derive the quantum-mechanical form of the isotropic component of the sum- and difference-frequency susceptibility and discuss its unusual spectral properties. We show that any coherent second-order nonlinear optical process in a system of randomly oriented molecules requires the medium to be chiral. and the incident frequencies to be different and nonzero. Furthermore, a minimum of two nondegenerate excited molecular states are needed for the isotropic part of the susceptibility to be nonvanishing. The rotationally invariant susceptibility is zero in the static field limit and shows exceptionally sensitive resonance and dephasing effects that are particular to chiral centers.

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DOI [BibTex]

2001


DOI [BibTex]


Reply to ``Comment on `Phenomenological damping in optical response tensors'{''}
Reply to “Comment on ‘Phenomenological damping in optical response tensors’”

Buckingham, A., Fischer, P.

PHYSICAL REVIEW A, 63(4), 2001 (article)

Abstract
We show that damping factors must not be incorporated in the perturbation of the ground state by a static electric field. If they are included, as in the theory of Stedman et al. {[}preceding Comment. Phys. Rev. A 63, 047801 (2001)], then there would be an electric dipole in the y direction induced in a hydrogen atom in the M-s = + 1/2 state by a static electric field in the x direction. Such a dipole is excluded by symmetry.

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DOI [BibTex]


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The coercivity of the melt-spun Sm-Fe-Ga-C permanent magnets and the effect of additives (Nb, Cu and Zr)

Zhang, J. X., Kleinschroth, I., Goll, D., Cuevas, F., Kronmüller, H.

{Journal of Physics-Condensed Matter}, 13(46):10487-10496, 2001 (article)

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[BibTex]

[BibTex]


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Hardness-depth profile of a carbon-implanted Ti-6Al-4V alloy and its relation to composition and microstructure

Kunert, M., Kienzle, O., Baretzky, B., Baker, S. P., Mittemeijer, E. J.

{Journal of Materials Research}, 16(8):2321-2335, 2001 (article)

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[BibTex]

[BibTex]


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New Sm(Co, Fe, Cu, Zr)(z) magnets with better temperature stability

Tang, W., Zhang, Y., Goll, D., Hadjipanayis, G. C., Kronmüller, H.

{Journal of Magnetism and Magnetic Materials}, 226(Sp. Iss. SI):1365-1366, 2001 (article)

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[BibTex]

[BibTex]


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Hydrogen in nanostructured vanadium-hydrogen systems

Orimo, S., Kimmerle, F., Majer, G.

{Physical Review B}, 63(9), 2001 (article)

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[BibTex]

[BibTex]


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Diffusion of hydrogen in heterogeneous systems

Herrmann, A., Schimmele, L., Mössinger, J., Hirscher, M., Kronmüller, H.

{Applied Physics A-Materials Science \& Processing}, 72(2):197-208, 2001 (article)

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[BibTex]

[BibTex]


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Structural vacancies in B2-CoAl and NiAl

Meyer, B., Bester, G., Fähnle, M.

{Scripta Materialia}, 44, pages: 2485-2488, 2001 (article)

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[BibTex]

[BibTex]


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Grain boundary phase transition in the Cu-Bi system

Straumal, B. B., Prokofyev, S. I., Chang, L.-S., Sluchanko, N. E., Baretzky, B., Gust, W., Mittemeijer, E. J.

{Diffusion and Defect Forum}, 194-199, pages: 1343-1348, 2001 (article)

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[BibTex]

[BibTex]


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Carbon nanostructures: an efficient hydrogen storage medium for fuel cells

Atkinson, K., Roth, S., Hirscher, M., Grünwald, W.

{Fuel Cells Bulletin}, 4(38):9-12, 2001 (article)

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[BibTex]

[BibTex]


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Magnetic domains in nanostructured media studied with M-TXM

Fischer, P., Eimüller, T., Schütz, G., Bayreuther, G., Tsunashima, S., Tagaki, N., Denbeaux, G., Attwood, D.

{Journal of Synchrotron Radiation}, 8, pages: 325-327, 2001 (article)

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[BibTex]

[BibTex]


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Compound formation and abrasion resistance of ion-implanted Ti6Al4V

Schmidt, H., Schminke, A., Schmiedgen, M., Baretzky, B.

{Acta Materialia}, 49, pages: 487-495, 2001 (article)

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[BibTex]

[BibTex]


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Interpretation of ab initio total energy results in a chemical language: I. Formalism and implementation into a mixed-basis pseudopotential code

Bester, G., Fähnle, M.

{Journal of Physics-Condensed Matter}, 13(50):11541-11550, 2001 (article)

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[BibTex]

[BibTex]


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Faceting of \sum3 and \sum9 grain boundaries in copper

Straumal, B. B., Polyakov, S. A., Bischoff, E., Gust, W., Mittemeijer, E. J.

{Interface Science}, 9(3-4):287-292, 2001 (article)

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[BibTex]

[BibTex]


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Generation and application of ultra-high-intensity magnetic field gradient pulses for NMR spectroscopy

Galvosas, P., Stallmach, F., Seiffert, G., Karger, J., Kaess, U., Majer, G.

{Journal of Magnetic Resonance}, 151(2):260-268, 2001 (article)

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[BibTex]

[BibTex]


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Formation and structure of highly over-stoichiometric LaNi5+x (x\textasciitilde1) alloys obtained by manifold non-equilibrium methods

Cuevas, F., Latroche, M., Hirscher, M., Percheron-Guegan, A.

{Journal of Alloys and Compounds}, 323, pages: 4-7, 2001 (article)

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[BibTex]

[BibTex]


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Hydrogen permeability measurement through Pd, Ni and Fe membranes

Yamakawa, K., Ege, M., Ludescher, B., Hirscher, M., Kronmüller, H.

{Journal of Alloys and Compounds}, 321(1):17-23, 2001 (article)

mms

[BibTex]

[BibTex]


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Ab-initio statistical mechanics for the phase diagram of NiAl including the effect of vacancies

Lechermann, F., Fähnle, M.

{Physica Status Solidi B-Basic Research}, 224(2):R4-R6, 2001 (article)

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[BibTex]

[BibTex]


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Uniaxial orientational order-disorder transitions in diammine magnesium halides, Mg(ND3)2Cl2 and Mg(ND3)2Br2, investigated by neutron diffraction

Leineweber, A., Jacobs, H., Fischer, P., Böttger, G.

{Journal of Solid State Chemistry}, 156(2):487-499, 2001 (article)

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[BibTex]

[BibTex]


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XMCD study of the Ruddlesden-Popper Phase La1.2Nd0.2Sr1.6Mn2O7

Weigand, F., Goering, E., Geissler, J., Justen, M., Dörr, K., Ruck, K., Schütz, G.

{Journal of Synchrotron Radiation}, 8, pages: 431-433, 2001 (article)

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DOI [BibTex]

DOI [BibTex]


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Nonlinear magnetoelastic effect in ultrathin epitaxial fcc Co (001) films: an ab-initio study

Komelj, M., Fähnle, M.

{Journal of Magnetism and Magnetic Materials}, 224, pages: L1-L4, 2001 (article)

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[BibTex]

[BibTex]


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Element-specific imaging of magnetic domains at 25 nm spatial Resolution using soft X-ray microscopy

Fischer, P., Eimüller, T., Schütz, G., Denbeaux, G., Pearson, A., Johnson, L., Attwood, D., Tsunashima, S., Kumazawa, M., Takagi, N., Köhler, M., Bayreuther, G.

{Review of Scientific Instruments}, 72, pages: 2322-2324, 2001 (article)

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[BibTex]

[BibTex]


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Magnetization reversal of a multilayered FeGd dot array imaged by transmission X-ray microscopy

Eimüller, T., Scholz, M., Guttmann, P., Fischer, P., Köhler, M., Bayreuther, G., Schmahl, G., Schütz, G.

{Journal of Applied Physics}, 89, pages: 7162-7164, 2001 (article)

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[BibTex]

[BibTex]


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Ho-Fe - Garnet soft XMCD measurements below and above the compensation temperature

Goering, E., Gold, S., Schütz, G.

{Journal of Synchrotron Radiation}, 8, pages: 422-424, 2001 (article)

mms

DOI [BibTex]

DOI [BibTex]