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1,036 results on '"Wuttig, M."'

1. Metavalent bonding in crystalline solids: how does it collapse?

Author

Guarneri, L., Jakobs, S., von Hoegen, A., Maier, S., Cojocaru-Mirédin, O., Raghuwanshi, M., Drögeler, M., Stampfer, C., Lobo, R. P. S. M., Piarristeguy, A., Pradel, A., Xu, M., and Wuttig, M.

Subjects
Condensed Matter - Materials Science
Abstract

The chemical bond is one of the most powerful, yet controversial concepts in chemistry, explaining property trends in solids. Recently, a novel type of chemical bonding has been identified in several higher chalcogenides, characterized by a unique property portfolio, unconventional bond breaking and sharing of about one electron between adjacent atoms. Metavalent bonding is a fundamental type of bonding besides covalent, ionic and metallic bonding, raising the pertinent question, if there is a well-defined transition between metavalent and covalent bonding. For three different pseudo-binary lines, namely GeTe1-xSex, Sb2Te3(1-x)Se3x and Bi2-2xSb2xSe3, a sudden drop in several properties, including the optical dielectric constant, the Born effective charge, the electrical conductivity as well as the bond breaking is observed once a critical Se or Sb concentration is reached. This finding provides a blueprint to explore the impact of metavalent bonding on attractive properties utilized in phase change materials and thermoelectrics.

Published
2020

2. Discovering electron transfer driven changes in chemical bonding in lead chalcogenides (PbX, where X = Te, Se, S, O)

Author

Maier, S., Steinberg, S., Cheng, Y., Schön, Carl-Friedrich, Schumacher, M., Mazzarello, R., Golub, P., Nelson, R., Cojocaru-Mirédin, O., Raty, J. -Y., and Wuttig, M.

Subjects
Condensed Matter - Materials Science
Abstract

Understanding the nature of chemical bonding in solids is crucial to comprehend the physical and chemical properties of a given compound. To explore changes in chemical bonding in lead chalcogenides (PbX, where X = Te, Se, S, O), a combination of property-, bond breaking- and quantum-mechanical bonding descriptors have been applied. The outcome of our explorations reveals an electron transfer driven transition from metavalent bonding in PbX (X = Te, Se, S) to iono-covalent bonding in beta-PbO. Metavalent bonding is characterized by adjacent atoms being held together by sharing about a single electron and small electron transfer (ET). The transition from metavalent to iono-covalent bonding manifests itself in clear changes in these quantum-mechanical descriptors (ES and ET), as well as in property-based descriptors (i.e. Born effective charge, dielectric function, effective coordination number (ECON) and mode-specific Grueneisen parameter, and in bond breaking descriptors (PME). Metavalent bonding collapses, if significant charge localization occurs at the ion cores (ET) and/or in the interatomic region (ES). Predominantly changing the degree of electron transfer opens possibilities to tailor materials properties such as the chemical bond and electronic polarizability, optical band gap and optical interband transitions characterized by the imaginary part of the dielectric function. Hence, the insights gained from this study highlight the technological relevance of the concept of metavalent bonding and its potential for materials design.

Published
2020

5. Switching Casimir forces with Phase Change Materials

Author

Torricelli, G., van Zwol, P. J., Shpak, O., Binns, C., Palasantzas, G., Svetovoy, B. J. Kooi V. B., and Wuttig, M.

Subjects
Condensed Matter - Materials Science
Abstract

We demonstrate here a controllable variation in the Casimir force. Changes in the force of up to 20% at separations of ~100 nm between Au and AgInSbTe (AIST) surfaces were achieved upon crystallization of an amorphous sample of AIST. This material is well known for its structural transformation, which produces a significant change in the optical properties and is exploited in optical data storage systems. The finding paves the way to the control of forces in nanosystems, such as micro- or nanoswitches by stimulating the phase change transition via localized heat sources., Comment: 7 pages, 3 figures The AFM images for the inset in Fig.2 were replaced with new ones as obtained with tips having high aspect ratio

Published
2010
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6. Adaptive modulations of martensites

Author

Kaufmann, S., Roessler, U. K., Heczko, O., Wuttig, M., Buschbeck, J., Schultz, L., and Fahler, S.

Subjects
Condensed Matter - Materials Science
Abstract

Modulated phases occur in numerous functional materials like giant ferroelectrics and magnetic shape memory alloys. To understand the origin of these phases, we review and generalize the concept of adaptive martensite. As a starting point, we investigate the coexistence of austenite, adaptive 14M phase and tetragonal martensite in Ni-Mn-Ga magnetic shape memory alloy epitaxial films. The modulated martensite can be constructed from nanotwinned variants of a tetragonal martensite phase. By combining the concept of adaptive martensite with branching of twin variants, we can explain key features of modulated phases from a microscopic view. This includes phase stability, the sequence of 6M-10M-NM intermartensitic transitions, and magnetocrystalline anisotropy., Comment: 4 pages manuscript, 8 pages supplement

Published
2009
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7. Combinatorial discovery of a lead-free morphotropic phase boundary in a thin-film piezoelectric perovskite

Author

Fujino, S., Murakami, M., Varatharajan, A., Lim, S. -H., Nagarajan, V., Fennie, C. J., Wuttig, M., Salamanca-Riba, L., and Takeuchi, I.

Subjects
Condensed Matter - Materials Science
Abstract

We report on the discovery of a lead-free morphotropic phase boundary in Sm doped BiFeO3 with a simple perovskite structure using the combinatorial thin film strategy. The boundary is a rhombohedral to pseudo-orthorhombic structural transition which exhibits a ferroelectric (FE) to antiferroelectric (AFE) transition at approximately Bi0.86Sm0.14FeO3 with dielectric constant and out-of-plane piezoelectric coefficient comparable to those of epitaxial (001) oriented Pb(Zr,Ti)O3 (PZT) thin films at the MPB. The discovered composition may be a strong candidate of a Pb-free piezoelectric replacement of PZT., Comment: 16 pages, 5 figures, submitted to Applied Physics Letters

Published
2008
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12. Multiferroic $BaTiO_{3}-CoFe_{2}O_{4}$ Nanostructures

Author

Zheng, H., Wang, J., Lofland, S. E., Ma, Z., Mohaddes-Ardabili, L., Zhao, T., Salamanca-Riba, L., Shinde, S. R., Ogale, S. B., Bai, F., Viehland, D., Jia, Y., Schlom, D. G., Wuttig, M., Roytburd, A., and Ramesh, R.

Published
2004

20. Changes in Electronic Structure and Chemical Bonding upon Crystallization of the Phase Change Material GeSb₂Te₄

Author

Klein, Andreas, Dieker, H., Späth, B., Fons, P., Kolobov, A., Steimer, C., Wuttig, M., Klein, Andreas, Dieker, H., Späth, B., Fons, P., Kolobov, A., Steimer, C., and Wuttig, M.

Abstract

High-resolution photoelectron spectroscopy of in situ prepared films of GeSb₂Te₄ reveals significant differences in electronic and chemical structure between the amorphous and the crystalline phase. Evidence for two different chemical environments of Ge and Sb in the amorphous structure is found. This observation can explain the pronounced property contrast between both phases and provides new insight into the formation of the amorphous state.

Published
2022

30. Far-infrared Near-field Optical Imaging and Kelvin Probe Force Microscopy of Laser-crystallized and amorphized Phase Change Material Ge₃Sb₂Te₆

Author

Barnett, J., Wehmeier, L., Heßler, A., Lewin, M., Pries, J., Wuttig, M., Klopf, J. M., Kehr, S. C., Eng, L. M., and Taubner, T.

Subjects
metavalent bonding, scattering-type scanning near-field optical microscopy, free-electron laser, optical switching, GST, phase change material, Kelvin probe force microscopy
Abstract

Chalcogenide phase change materials reversibly switch between non-volatile states with vastly different optical properties, enabling novel active nanophotonic devices. However, a fundamental understanding of their laser-switching behavior is lacking and the resulting local optical properties are unclear at the nanoscale. Here, we combine infrared scattering-type scanning near-field optical microscopy (SNOM) and Kelvin probe force microscopy (KPFM) to investigate four states of laser-switched Ge3Sb2Te6 (as-deposited amorphous, crystallized, reamorphized, and recrystallized) with nanometer lateral resolution. We find SNOM especially sensitive to differences between crystalline and amorphous states, while KPFM has higher sensitivity to changes introduced by melt-quenching. Using illumination from a free-electron laser, we employ that far-infrared (THz) SNOM is more sensitive to free charge carriers compared to mid-infrared SNOM and prove that the local conductivity of crystalline states depends on the switching process. This insight into the local switching of optical properties is essential for developing active nanophotonic devices.

Published
2021

36. Poster: Memristive Systems

Author

Ho Yoon, Jung, primary, Jung, Hyung-Suk, additional, Hwan Lee, Min, additional, Hwan Kim, Gun, additional, Ji Song, Seul, additional, Yeong Seok, Jun, additional, Jean Yoon, Kyung, additional, Seong Hwang, Cheol, additional, Besland, M.-P., additional, Tranchant, J., additional, Souchier, E., additional, Moreau, P., additional, Salmon, S., additional, Corraze, B., additional, Janod, E., additional, Cario, L., additional, Zazpe, Raúl, additional, Ungureanu, Mariana, additional, Llopis, Roger, additional, Golmar, Federico, additional, Stoliar, Pablo, additional, Casanova, Félix, additional, Eduardo Hueso, Luis, additional, Hermes, C., additional, Wimmer, M., additional, Menzel, S., additional, Fleck, K., additional, Rana, V., additional, Salinga, M., additional, Böttger, U., additional, Bruchhaus, R., additional, Wuttig, M., additional, Waser, R., additional, Lentz, F., additional, Rösgen, B., additional, Selle, T., additional, Marchewka, Astrid, additional, Menzel, Stephan, additional, Böttger, Ulrich, additional, Waser, Rainer, additional, Hoskins, Brian, additional, Alibart, Fabien, additional, Strukov, Dmitri, additional, Pellegrino, Luca, additional, Manca, Nicola, additional, Kanki, Teruo, additional, Tanaka, Hidekazu, additional, Biasotti, Michele, additional, Bellingeri, Emilio, additional, Sergio Siri, Antonio, additional, Marré, Daniele, additional, M. Padilha, Antonio Claudio, additional, Martini Dalpian, Gustavo, additional, Reily Rocha, Alexandre, additional, Prodromakis, Themistoklis, additional, Salaoru, Iulia, additional, Khiat, Ali, additional, Toumazou, Christopher, additional, Gale, Ella M., additional, Madhavan, A., additional, Adam, G., additional, Alibart, F., additional, Gao, L., additional, Strukov, D. B., additional, Wamwangi, D., additional, Welnic, W., additional, Gholipour, Behrad, additional, Huang, Chung-Che, additional, Anastasopoulos, Alexandros, additional, Al-Saab, Feras, additional, Hayden, Brian E., additional, Hewak, Daniel W., additional, Lan, Rui, additional, Endo, Rie, additional, Kuwahara, Masashi, additional, Kobayashi, Yoshinao, additional, Susa, Masahiro, additional, Baumeister, Paul, additional, Wortmann, Daniel, additional, Blügel, Stefan, additional, Mazzarello, Riccardo, additional, Li, Yan, additional, Zhang, Wei, additional, Ronneberger, Ider, additional, Simon, Ronnie, additional, Gallus, Jens, additional, Bessas, Dimitrios, additional, Sergueev, Ilya, additional, Wille, Hans-Christian, additional, Pierre Hermann, Raphaël, additional, Luckas, Jennifer, additional, Rausch, Pascal, additional, Krebs, Daniel, additional, Zalden, Peter, additional, Boltz, Janika, additional, Raty, Jean-Yves, additional, Salinga, Martin, additional, Longeaud, Christophe, additional, Wuttig, Matthias, additional, Kim, Haeri, additional, Kim, Dong-Wook, additional, Phark, Soo-Hyon, additional, Hong, Seungbum, additional, Park, C., additional, Herpers, A., additional, Verbeeck, J., additional, Egoavil, R., additional, Borgatti, F., additional, Panaccione, G., additional, Offi, F., additional, Dittmann, R., additional, Clima, Sergiu, additional, Sankaran, Kiroubanand, additional, Mees, Maarten, additional, Yin Chen, Yang, additional, Goux, Ludovic, additional, Govoreanu, Bogdan, additional, Wouters, Dirk J., additional, Kittl, Jorge, additional, Jurczak, Malgorzata, additional, Pourtois, Geoffrey, additional, Calka, P., additional, Martinez, E., additional, Delaye, V., additional, Lafond, D., additional, Audoit, G., additional, Mariolle, D., additional, Chevalier, N., additional, Grampeix, H., additional, Cagli, C., additional, Jousseaume, V., additional, Guedj, C., additional, Shrestha, Pragya, additional, Ochia, Adaku, additional, Cheung, Kin. P., additional, Campbell, Jason, additional, Baumgart, Helmut, additional, Harris, Gary, additional, Scherff, Malte, additional, Meyer, Bjoern, additional, Scholz, Julius, additional, Hoffmann, Joerg, additional, Jooss, Christian, additional, Xiao, Bo, additional, Tada, Tomofumi, additional, Gu, Tingkun, additional, Tawara, Arihiro, additional, Watanabe, Satoshi, additional, Young, Tai-Fa, additional, Yang, Ya-Liang, additional, Chang, Ting-Chang, additional, Hsu, Kuang-Ting, additional, Chen, Chao-Yu, additional, Burkert, A, additional, Valov, I., additional, Staikov, G., additional, van den Hurk, Jan, additional, Valov, Ilia, additional, Tappertzhofen, Stefan, additional, van der Hurk, Jan, additional, Hoskins, B., additional, Kim, Gun Hwan, additional, Seok, Jun Yeong, additional, Ho Yoon, Jeong, additional, Yoon, Jung Ho, additional, Yoon, Kyung Jin, additional, Shuai, Yao, additional, Wu, Chuangui, additional, Zhang, Wanli, additional, Zhou, Shengqiang, additional, Bürger, Danilo, additional, Slesazeck, Stefan, additional, Mikolajick, Thomas, additional, Helm, Manfred, additional, Schmidt, Heidemarie, additional, Gale, Ella, additional, Pearson, David, additional, Kitson, Stephen, additional, Adamatzky, Andrew, additional, Costello, Ben de Lacy, additional, Lehtonen, Eero, additional, Poikonen, Jussi, additional, Laiho, Mika, additional, Kanerva, Pentti, additional, Lim, Hyungkwang, additional, Jang, Ho-won, additional, Jeong, Doo Seok, additional, Cao, Xun, additional, Jiang, Meng, additional, Zhang, Feng, additional, Liu, Xinjun, additional, Jin, Ping, additional, Zhang, Kai, additional, Tangirala, Madhavi, additional, Kittiwatanakul, Salinporn, additional, Lu, Jiwei, additional, Wolf, Stuart, additional, Pallem, Venkateswara, additional, Dussarrat, Christian, additional, Pinto, S., additional, Krishna, R., additional, Dias, C., additional, Pimentel, G., additional, Oliveira, G. N. P., additional, Teixeira, J. M., additional, Aguiar, P., additional, Titus, E., additional, Gracio, J., additional, Ventura, J., additional, and Araujo, J. P., additional

Published
2013
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37. Nanosession: Calorics

Author

Wu, L., primary, Meng, Q., additional, Jooss, Ch., additional, Zheng, J., additional, Inada, H., additional, Su, D., additional, Li, Q., additional, Zhu, Y., additional, Thomas, Andy, additional, Münzenberg, Markus, additional, Heiliger, Christian, additional, Rabel, Elias, additional, Mavropoulos, Phivos, additional, Thiess, Alexander, additional, Zeller, Rudolf, additional, Fukushima, Tetsuya, additional, Vu, Nguyen D., additional, Sato, Kazunori, additional, Katayama-Yoshida, Hiroshi, additional, Kovacik, Roman, additional, Dederichs, Peter H., additional, Blügel, Stefan, additional, Costi, Theo, additional, Zlatic, Veljko, additional, Shkabko, A., additional, Sagarna, L., additional, Populoh, S., additional, Karvonen, L., additional, Weidenkaff, A., additional, Lange, F. R. L., additional, Siegert, K. S., additional, Wuttig, M., additional, Poudeu, Pierre F. P., additional, Makongo, Julien P. A., additional, Sahoo, Pranati, additional, Yuanfeng, Liu, additional, Zhou, Xiaoyuan, additional, and Uher, Ctirad, additional

Published
2013
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44. Kinetics of crystal nucleation in undercooled droplets of Sb- and Te-based alloys used for phase change recording

Author

Kalb, J.A., Spaepen, F., and Wuttig, M.

Subjects
Tellurium -- Electric properties, Alloys -- Electric properties, Phase transformations (Statistical physics) -- Analysis, Physics
Abstract

Droplets of molten alloys of composition Ge12Sb88, Ag0.055In0.065Sb0.59Te0.29, Ge4Sb1Te5, and Ge2Sb2Te5, used for optical data storage, surrounded by a molten dehydrated B2O3 flux is undercooled to 40-80 K below their liquidus temperature in a differential thermal analyzer. Results reveal that it is the presence of an incubation time that makes amorphization and therefore phase change recording possible in both optical and electronic media.

Published
2005

45. Crystal morphology and nucleation in thin films of amorphous Te alloys used for phase change recording

Author

Kalb, J.A., Wen, C.Y., Spaepen, Frans, Dieker, H., and Wuttig, M.

Subjects
Dielectric films -- Design and construction, Thin films -- Design and construction, Amorphous semiconductors -- Electric properties, Germanium -- Electric properties, Physics
Abstract

Ex situ transmission electron microscopy (TEM) is used to study the crystal morphology in sputtered amorphous Ge4Sb1Te5, Ge2Sb2Te5, and Ag0.055In0.065Sb0.59Te0.29 thin films used for phase change recording. Cross-sectional TEM reveal that crystals only nucleate heterogeneously at the film surface.

Published
2005

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