Search

Your search keyword '"Kisielewski, J"' showing total 152 results
Start Over Author "Kisielewski, J"
152 results on '"Kisielewski, J"'

1. Magnetization statics and dynamics in (Ir/Co/Pt)$_6$ multilayers with Dzyaloshinskii-Moriya interaction

Author

Dhiman, A. K., Gieniusz, R., Gruszecki, P., Kisielewski, J., Matczak, M., Kurant, Z., Sveklo, I., Guzowska, U., Tekielak, M., Stobiecki, F., and Maziewski, A.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Magnetic multilayers of (Ir/Co/Pt)$_6$ with interfacial Dzyaloshinskii-Moriya interaction (IDMI) were deposited by magnetron sputtering with Co thickness $d=1.8$ nm. Exploiting magneto-optical Kerr effect in longitudinal mode microscopy, magnetic force microscopy, and vibrating sample magnetometry, the magnetic field-driven evolution of domain structures and magnetization hysteresis loops have been studied. The existence of weak stripe domains structure was deduced -- tens micrometers size domains with in-plane "core" magnetization modulated by hundred of nanometers domains with out-of-plane magnetization. Micromagnetic simulations interpreted such magnetization distribution. Quantitative evaluation of IDMI was carried out using Brillouin light scattering (BLS) spectroscopy as the difference between Stokes and anti-Stokes peak frequencies $\Delta f$. Due to the additive nature of IDMI, the asymmetric combination of Ir and Pt covers led to large values of effective IDMI energy density $D_\mathrm{eff}$. It was found that Stokes and anti-Stokes frequencies as well as $\Delta f$, measured as a function of in-plane applied magnetic field, show hysteresis. These results are explained under the consideration of the influence of IDMI on the dynamics of the in-plane magnetized "core" with weak stripe domains.

Published
2022
Full Text
View/download PDF

6. Predictive performance of multi-model ensemble forecasts of COVID-19 across European nations

Author

Sherratt, K., Gruson, H., Grah, R., Johnson, H., Niehus, R., Prasse, B., Sandmann, F., Deuschel, J., Wolffram, D., Abbott, S., Ullrich, A., Gibson, G., Ray, E. L., Reich, N. G., Sheldon, D., Wang, Y., Wattanachit, N., Wang, L., Trnka, J., Obozinski, G., Sun, T., Thanou, D., Pottier, L., Krymova, E., Meinke, J. H., Barbarossa, M. V., Leithäuser, N., Mohring, J., Schneider, J., Wlazlo, J., Fuhrmann, J., Lange, B., Rodiah, I., Baccam, P., Gurung, H., Stage, S., Suchoski, B., Budzinski, J., Walraven, R., Villanueva, I., Tucek, V., Smíd, M., Zajícek, M., Pérez Alvarez, C., Reina, B., Bosse, N. I., Meakin, S., Castro, L., Fairchild, G., Michaud, I., Osthus, D., Alaimo Di Loro, P., Maruotti, A., Eclerová, V., Kraus, A., Kraus, D., Pribylova, L., Dimitris, B., Li, M. L., Saksham, S., Dehning, J., Mohr, S., Priesemann, V., Redlarski, G., Bejar, B., Ardenghi, G., Parolini, N., Ziarelli, G., Bock, Wolfgang, Heyder, S., Hotz, T., E. Singh, D., Guzman-Merino, M., Aznarte, J. L., Moriña, D., Alonso, S., Alvarez, E., López, D., Prats, C., Burgard, J. P., Rodloff, A., Zimmermann, T., Kuhlmann, A., Zibert, J., Pennoni, F., Divino, F., Català, M., Lovison, G., Giudici, P., Tarantino, B., Bartolucci, F., Jona Lasinio, G., Mingione, M., Farcomeni, A., Srivastava, A., Montero-Manso, P., Adiga, A., Hurt, B., Lewis, B., Marathe, M., Porebski, P., Venkatramanan, S., Bartczuk, R., Dreger, F., Gambin, A., Gogolewski, K., Gruziel-S?omka, M., Krupa, B., Moszynski, A., Niedzielewski, K., Nowosielski, J., Radwan, M., Rakowski, F., Semeniuk, M., Szczurek, E., Zieli?ski, J., Kisielewski, J., Pabjan, B., Kheifetz, Y., Kirsten, H., Scholz, M., Biecek, P., Bodych, M., Filinski, M., Idzikowski, R., Krueger, T., Ozanski, T., Bracher, J., Funk, S., Sherratt, K., Gruson, H., Grah, R., Johnson, H., Niehus, R., Prasse, B., Sandmann, F., Deuschel, J., Wolffram, D., Abbott, S., Ullrich, A., Gibson, G., Ray, E. L., Reich, N. G., Sheldon, D., Wang, Y., Wattanachit, N., Wang, L., Trnka, J., Obozinski, G., Sun, T., Thanou, D., Pottier, L., Krymova, E., Meinke, J. H., Barbarossa, M. V., Leithäuser, N., Mohring, J., Schneider, J., Wlazlo, J., Fuhrmann, J., Lange, B., Rodiah, I., Baccam, P., Gurung, H., Stage, S., Suchoski, B., Budzinski, J., Walraven, R., Villanueva, I., Tucek, V., Smíd, M., Zajícek, M., Pérez Alvarez, C., Reina, B., Bosse, N. I., Meakin, S., Castro, L., Fairchild, G., Michaud, I., Osthus, D., Alaimo Di Loro, P., Maruotti, A., Eclerová, V., Kraus, A., Kraus, D., Pribylova, L., Dimitris, B., Li, M. L., Saksham, S., Dehning, J., Mohr, S., Priesemann, V., Redlarski, G., Bejar, B., Ardenghi, G., Parolini, N., Ziarelli, G., Bock, Wolfgang, Heyder, S., Hotz, T., E. Singh, D., Guzman-Merino, M., Aznarte, J. L., Moriña, D., Alonso, S., Alvarez, E., López, D., Prats, C., Burgard, J. P., Rodloff, A., Zimmermann, T., Kuhlmann, A., Zibert, J., Pennoni, F., Divino, F., Català, M., Lovison, G., Giudici, P., Tarantino, B., Bartolucci, F., Jona Lasinio, G., Mingione, M., Farcomeni, A., Srivastava, A., Montero-Manso, P., Adiga, A., Hurt, B., Lewis, B., Marathe, M., Porebski, P., Venkatramanan, S., Bartczuk, R., Dreger, F., Gambin, A., Gogolewski, K., Gruziel-S?omka, M., Krupa, B., Moszynski, A., Niedzielewski, K., Nowosielski, J., Radwan, M., Rakowski, F., Semeniuk, M., Szczurek, E., Zieli?ski, J., Kisielewski, J., Pabjan, B., Kheifetz, Y., Kirsten, H., Scholz, M., Biecek, P., Bodych, M., Filinski, M., Idzikowski, R., Krueger, T., Ozanski, T., Bracher, J., and Funk, S.

Abstract

Methods: We used open-source tools to develop a public European COVID-19 Forecast Hub. We invited groups globally to contribute weekly forecasts for COVID-19 cases and deaths reported by a standardised source for 32 countries over the next 1–4 weeks. Teams submitted forecasts from March 2021 using standardised quantiles of the predictive distribution. Each week we created an ensemble forecast, where each predictive quantile was calculated as the equally-weighted average (initially the mean and then from 26th July the median) of all individual models’ predictive quantiles. We measured the performance of each model using the relative Weighted Interval Score (WIS), comparing models’ forecast accuracy relative to all other models. We retrospectively explored alternative methods for ensemble forecasts, including weighted averages based on models’ past predictive performance. Results: Over 52 weeks, we collected forecasts from 48 unique models. We evaluated 29 models’ forecast scores in comparison to the ensemble model. We found a weekly ensemble had a consistently strong performance across countries over time. Across all horizons and locations, the ensemble performed better on relative WIS than 83% of participating models’ forecasts of incident cases (with a total N=886 predictions from 23 unique models), and 91% of participating models’ forecasts of deaths (N=763 predictions from 20 models). Across a 1–4 week time horizon, ensemble performance declined with longer forecast periods when forecasting cases, but remained stable over 4 weeks for incident death forecasts. In every forecast across 32 countries, the ensemble outperformed most contributing models when forecasting either cases or deaths, frequently outperforming all of its individual component models. Among several choices of ensemble methods we found that the most influential and best choice was to use a median average of models instead of using the mean, regardless of methods of weighting component forecast mod

Published
2023
Full Text
View/download PDF

7. Predictive performance of multi-model ensemble forecasts of COVID-19 across European nations

Author

Sherratt, K, Gruson, H, Grah, R, Johnson, H, Niehus, R, Prasse, B, Sandmann, F, Deuschel, J, Wolffram, D, Abbott, S, Ullrich, A, Gibson, G, L Ray, E, G Reich, N, Sheldon, D, Wang, Y, Wattanachit, N, Wang, L, Trnka, J, Obozinski, G, Sun, T, Thanou, D, Pottier, L, Krymova, E, H Meinke, J, Vittoria Barbarossa, M, Leithäuser, N, Mohring, J, Schneider, J, Włazło, J, Fuhrmann, J, Lange, B, Rodiah, I, Baccam, P, Gurung, H, Stage, S, Suchoski, B, Budzinski, J, Walraven, R, Villanueva, I, Tucek, V, Smid, M, Zajíček, M, Pérez Álvarez, C, Reina, B, I Bosse, N, R Meakin, S, Castro, L, Fairchild, G, Michaud, I, Osthus, D, Alaimo Di Loro, P, Maruotti, A, Eclerová, V, Kraus, A, Kraus, D, Pribylova, L, Dimitris, B, Lingzhi Li, M, Saksham, S, Dehning, J, Mohr, S, Priesemann, V, Redlarski, G, Bejar, B, Ardenghi, G, Parolini, N, Ziarelli, G, Bock, W, Heyder, S, Hotz, T, E Singh, D, Guzman-Merino, M, L Aznarte, J, Moriña, D, Alonso, S, Álvarez, E, López, D, Prats, C, Pablo Burgard, J, Rodloff, A, Zimmermann, T, Kuhlmann, A, Zibert, J, Pennoni, F, Divino, F, Català, M, Lovison, G, Giudici, P, Tarantino, B, Bartolucci, F, Jona Lasinio, G, Mingione, M, Farcomeni, A, Srivastava, A, Montero-Manso, P, Adiga, A, Hurt, B, Lewis, B, Marathe, M, Porebski, P, Venkatramanan, S, P Bartczuk, R, Dreger, F, Gambin, A, Gogolewski, K, Gruziel-Słomka, M, Krupa, B, Moszyński, A, Niedzielewski, K, Nowosielski, J, Radwan, M, Rakowski, F, Semeniuk, M, Szczurek, E, Zieliński, J, Kisielewski, J, Pabjan, B, Kirsten, H, Kheifetz, Y, Scholz, M, Biecek, P, Bodych, M, Filinski, M, Idzikowski, R, Krueger, T, Ozanski, T, Bracher, J, Funk, S, Katharine Sherratt, Hugo Gruson, Rok Grah, Helen Johnson, Rene Niehus, Bastian Prasse, Frank Sandmann, Jannik Deuschel, Daniel Wolffram, Sam Abbott, Alexander Ullrich, Graham Gibson, Evan L Ray, Nicholas G Reich, Daniel Sheldon, Yijin Wang, Nutcha Wattanachit, Lijing Wang, Jan Trnka, Guillaume Obozinski, Tao Sun, Dorina Thanou, Loic Pottier, Ekaterina Krymova, Jan H Meinke, Maria Vittoria Barbarossa, Neele Leithäuser, Jan Mohring, Johanna Schneider, Jaroslaw Włazło, Jan Fuhrmann, Berit Lange, Isti Rodiah, Prasith Baccam, Heidi Gurung, Steven Stage, Bradley Suchoski, Jozef Budzinski, Robert Walraven, Inmaculada Villanueva, Vit Tucek, Martin Smid, Milan Zajíček, Cesar Pérez Álvarez, Borja Reina, Nikos I Bosse, Sophie R Meakin, Lauren Castro, Geoffrey Fairchild, Isaac Michaud, Dave Osthus, Pierfrancesco Alaimo Di Loro, Antonello Maruotti, Veronika Eclerová, Andrea Kraus, David Kraus, Lenka Pribylova, Bertsimas Dimitris, Michael Lingzhi Li, Soni Saksham, Jonas Dehning, Sebastian Mohr, Viola Priesemann, Grzegorz Redlarski, Benjamin Bejar, Giovanni Ardenghi, Nicola Parolini, Giovanni Ziarelli, Wolfgang Bock, Stefan Heyder, Thomas Hotz, David E Singh, Miguel Guzman-Merino, Jose L Aznarte, David Moriña, Sergio Alonso, Enric Álvarez, Daniel López, Clara Prats, Jan Pablo Burgard, Arne Rodloff, Tom Zimmermann, Alexander Kuhlmann, Janez Zibert, Fulvia Pennoni, Fabio Divino, Marti Català, Gianfranco Lovison, Paolo Giudici, Barbara Tarantino, Francesco Bartolucci, Giovanna Jona Lasinio, Marco Mingione, Alessio Farcomeni, Ajitesh Srivastava, Pablo Montero-Manso, Aniruddha Adiga, Benjamin Hurt, Bryan Lewis, Madhav Marathe, Przemyslaw Porebski, Srinivasan Venkatramanan, Rafal P Bartczuk, Filip Dreger, Anna Gambin, Krzysztof Gogolewski, Magdalena Gruziel-Słomka, Bartosz Krupa, Antoni Moszyński, Karol Niedzielewski, Jedrzej Nowosielski, Maciej Radwan, Franciszek Rakowski, Marcin Semeniuk, Ewa Szczurek, Jakub Zieliński, Jan Kisielewski, Barbara Pabjan, Holger Kirsten, Yuri Kheifetz, Markus Scholz, Przemyslaw Biecek, Marcin Bodych, Maciej Filinski, Radoslaw Idzikowski, Tyll Krueger, Tomasz Ozanski, Johannes Bracher, Sebastian Funk, Sherratt, K, Gruson, H, Grah, R, Johnson, H, Niehus, R, Prasse, B, Sandmann, F, Deuschel, J, Wolffram, D, Abbott, S, Ullrich, A, Gibson, G, L Ray, E, G Reich, N, Sheldon, D, Wang, Y, Wattanachit, N, Wang, L, Trnka, J, Obozinski, G, Sun, T, Thanou, D, Pottier, L, Krymova, E, H Meinke, J, Vittoria Barbarossa, M, Leithäuser, N, Mohring, J, Schneider, J, Włazło, J, Fuhrmann, J, Lange, B, Rodiah, I, Baccam, P, Gurung, H, Stage, S, Suchoski, B, Budzinski, J, Walraven, R, Villanueva, I, Tucek, V, Smid, M, Zajíček, M, Pérez Álvarez, C, Reina, B, I Bosse, N, R Meakin, S, Castro, L, Fairchild, G, Michaud, I, Osthus, D, Alaimo Di Loro, P, Maruotti, A, Eclerová, V, Kraus, A, Kraus, D, Pribylova, L, Dimitris, B, Lingzhi Li, M, Saksham, S, Dehning, J, Mohr, S, Priesemann, V, Redlarski, G, Bejar, B, Ardenghi, G, Parolini, N, Ziarelli, G, Bock, W, Heyder, S, Hotz, T, E Singh, D, Guzman-Merino, M, L Aznarte, J, Moriña, D, Alonso, S, Álvarez, E, López, D, Prats, C, Pablo Burgard, J, Rodloff, A, Zimmermann, T, Kuhlmann, A, Zibert, J, Pennoni, F, Divino, F, Català, M, Lovison, G, Giudici, P, Tarantino, B, Bartolucci, F, Jona Lasinio, G, Mingione, M, Farcomeni, A, Srivastava, A, Montero-Manso, P, Adiga, A, Hurt, B, Lewis, B, Marathe, M, Porebski, P, Venkatramanan, S, P Bartczuk, R, Dreger, F, Gambin, A, Gogolewski, K, Gruziel-Słomka, M, Krupa, B, Moszyński, A, Niedzielewski, K, Nowosielski, J, Radwan, M, Rakowski, F, Semeniuk, M, Szczurek, E, Zieliński, J, Kisielewski, J, Pabjan, B, Kirsten, H, Kheifetz, Y, Scholz, M, Biecek, P, Bodych, M, Filinski, M, Idzikowski, R, Krueger, T, Ozanski, T, Bracher, J, Funk, S, Katharine Sherratt, Hugo Gruson, Rok Grah, Helen Johnson, Rene Niehus, Bastian Prasse, Frank Sandmann, Jannik Deuschel, Daniel Wolffram, Sam Abbott, Alexander Ullrich, Graham Gibson, Evan L Ray, Nicholas G Reich, Daniel Sheldon, Yijin Wang, Nutcha Wattanachit, Lijing Wang, Jan Trnka, Guillaume Obozinski, Tao Sun, Dorina Thanou, Loic Pottier, Ekaterina Krymova, Jan H Meinke, Maria Vittoria Barbarossa, Neele Leithäuser, Jan Mohring, Johanna Schneider, Jaroslaw Włazło, Jan Fuhrmann, Berit Lange, Isti Rodiah, Prasith Baccam, Heidi Gurung, Steven Stage, Bradley Suchoski, Jozef Budzinski, Robert Walraven, Inmaculada Villanueva, Vit Tucek, Martin Smid, Milan Zajíček, Cesar Pérez Álvarez, Borja Reina, Nikos I Bosse, Sophie R Meakin, Lauren Castro, Geoffrey Fairchild, Isaac Michaud, Dave Osthus, Pierfrancesco Alaimo Di Loro, Antonello Maruotti, Veronika Eclerová, Andrea Kraus, David Kraus, Lenka Pribylova, Bertsimas Dimitris, Michael Lingzhi Li, Soni Saksham, Jonas Dehning, Sebastian Mohr, Viola Priesemann, Grzegorz Redlarski, Benjamin Bejar, Giovanni Ardenghi, Nicola Parolini, Giovanni Ziarelli, Wolfgang Bock, Stefan Heyder, Thomas Hotz, David E Singh, Miguel Guzman-Merino, Jose L Aznarte, David Moriña, Sergio Alonso, Enric Álvarez, Daniel López, Clara Prats, Jan Pablo Burgard, Arne Rodloff, Tom Zimmermann, Alexander Kuhlmann, Janez Zibert, Fulvia Pennoni, Fabio Divino, Marti Català, Gianfranco Lovison, Paolo Giudici, Barbara Tarantino, Francesco Bartolucci, Giovanna Jona Lasinio, Marco Mingione, Alessio Farcomeni, Ajitesh Srivastava, Pablo Montero-Manso, Aniruddha Adiga, Benjamin Hurt, Bryan Lewis, Madhav Marathe, Przemyslaw Porebski, Srinivasan Venkatramanan, Rafal P Bartczuk, Filip Dreger, Anna Gambin, Krzysztof Gogolewski, Magdalena Gruziel-Słomka, Bartosz Krupa, Antoni Moszyński, Karol Niedzielewski, Jedrzej Nowosielski, Maciej Radwan, Franciszek Rakowski, Marcin Semeniuk, Ewa Szczurek, Jakub Zieliński, Jan Kisielewski, Barbara Pabjan, Holger Kirsten, Yuri Kheifetz, Markus Scholz, Przemyslaw Biecek, Marcin Bodych, Maciej Filinski, Radoslaw Idzikowski, Tyll Krueger, Tomasz Ozanski, Johannes Bracher, and Sebastian Funk

Abstract

Background: Short-term forecasts of infectious disease contribute to situational awareness and capacity planning. Based on best practice in other fields and recent insights in infectious disease epidemiology, one can maximise forecasts’ predictive performance by combining independent models into an ensemble. Here we report the performance of ensemble predictions of COVID-19 cases and deaths across Europe from March 2021 to March 2022. Methods: We created the European COVID-19 Forecast Hub, an online open-access platform where modellers upload weekly forecasts for 32 countries with results publicly visualised and evaluated. We created a weekly ensemble forecast from the equally-weighted average across individual models’ predictive quantiles. We measured forecast accuracy using a baseline and relative Weighted Interval Score (rWIS). We retrospectively explored ensemble methods, including weighting by past performance. Results: We collected weekly forecasts from 48 models, of which we evaluated 29 models alongside the ensemble model. The ensemble had a consistently strong performance across countries over time, performing better on rWIS than 91% of forecasts for deaths (N=763 predictions from 20 models), and 83% forecasts for cases (N=886 predictions from 23 models). Performance remained stable over a 4-week horizon for death forecasts but declined with longer horizons for cases. Among ensemble methods, the most influential choice came from using a median average instead of the mean, regardless of weighting component models. Conclusions: Our results support combining independent models into an ensemble forecast to improve epidemiological predictions, and suggest that median averages yield better performance than methods based on means. We highlight that forecast consumers should place more weight on incident death forecasts than case forecasts at horizons greater than two weeks. Funding: European Commission, Ministerio de Ciencia, Innovación y Universidades, FEDER; Ag

Published
2023

10. Predictive performance of multi-model ensemble forecasts of COVID-19 across European nations

Author

Sherratt, K., primary, Gruson, H., additional, Grah, R., additional, Johnson, H., additional, Niehus, R., additional, Prasse, B., additional, Sandman, F., additional, Deuschel, J., additional, Wolffram, D., additional, Abbott, S., additional, Ullrich, A., additional, Gibson, G., additional, Ray, EL., additional, Reich, NG., additional, Sheldon, D., additional, Wang, Y., additional, Wattanachit, N., additional, Wang, L., additional, Trnka, J., additional, Obozinski, G., additional, Sun, T., additional, Thanou, D., additional, Pottier, L., additional, Krymova, E., additional, Barbarossa, MV., additional, Leithäuser, N., additional, Mohring, J., additional, Schneider, J., additional, Wlazlo, J., additional, Fuhrmann, J., additional, Lange, B., additional, Rodiah, I., additional, Baccam, P., additional, Gurung, H., additional, Stage, S., additional, Suchoski, B., additional, Budzinski, J., additional, Walraven, R., additional, Villanueva, I., additional, Tucek, V., additional, Šmíd, M., additional, Zajícek, M., additional, Pérez Álvarez, C., additional, Reina, B., additional, Bosse, NI., additional, Meakin, S., additional, Di Loro, P. Alaimo, additional, Maruotti, A., additional, Eclerová, V., additional, Kraus, A., additional, Kraus, D., additional, Pribylova, L., additional, Dimitris, B., additional, Li, ML., additional, Saksham, S., additional, Dehning, J., additional, Mohr, S., additional, Priesemann, V., additional, Redlarski, G., additional, Bejar, B., additional, Ardenghi, G., additional, Parolini, N., additional, Ziarelli, G., additional, Bock, W., additional, Heyder, S., additional, Hotz, T., additional, E. Singh, D., additional, Guzman-Merino, M., additional, Aznarte, JL., additional, Moriña, D., additional, Alonso, S., additional, Álvarez, E., additional, López, D., additional, Prats, C., additional, Burgard, JP., additional, Rodloff, A., additional, Zimmermann, T., additional, Kuhlmann, A., additional, Zibert, J., additional, Pennoni, F., additional, Divino, F., additional, Català, M., additional, Lovison, G., additional, Giudici, P., additional, Tarantino, B., additional, Bartolucci, F., additional, Jona Lasinio, G., additional, Mingione, M., additional, Farcomeni, A., additional, Srivastava, A., additional, Montero-Manso, P., additional, Adiga, A., additional, Hurt, B., additional, Lewis, B., additional, Marathe, M., additional, Porebski, P., additional, Venkatramanan, S., additional, Bartczuk, R., additional, Dreger, F., additional, Gambin, A., additional, Gogolewski, K., additional, Gruziel-Slomka, M., additional, Krupa, B., additional, Moszynski, A., additional, Niedzielewski, K., additional, Nowosielski, J., additional, Radwan, M., additional, Rakowski, F., additional, Semeniuk, M., additional, Szczurek, E., additional, Zielinski, J., additional, Kisielewski, J., additional, Pabjan, B., additional, Holger, K., additional, Kheifetz, Y., additional, Scholz, M., additional, Bodych, M., additional, Filinski, M., additional, Idzikowski, R., additional, Krueger, T., additional, Ozanski, T., additional, Bracher, J., additional, and Funk, S., additional

Published
2022
Full Text
View/download PDF

13. Origin of focused laser irradiation-induced enhancement of perpendicular magnetic anisotropy in Pt/Co/Pt thin films investigated by spatially resolved x-ray absorption spectroscopy.

Author

Amemiya, K., Sakamaki, M., Kisielewski, J., Kurant, Z., Sveklo, I., Tekielak, M., Maziewski, A., and Wawro, A.

Subjects
MAGNETIC anisotropy, X-ray absorption, PHOTOELECTRONS, MAGNETIZATION, EXTENDED X-ray absorption fine structure
Abstract

The origin of the focused single-pulse laser irradiation-induced changes in magnetic anisotropy of a Pt/Co/Pt film is investigated by the x-ray absorption near-edge structure and extended x-ray absorption fine structure techniques combined with the photoelectron emission microscope. A significant increase of the Co–Co bond length in both in-plane and out-of-plane directions is observed on the periphery of the laser spot, at which perpendicular magnetization appears. With increasing laser power density towards the center of the laser spot, anisotropic structural changes are observed accompanied by the reappearance of in-plane magnetization. The enhancement of perpendicular magnetization is attributed to the lattice expansion-induced magnetoelastic effect, while the in-plane compressive strain in the Co film is suggested to be the origin of the reappearance of in-plane magnetization at higher laser power densities. [ABSTRACT FROM AUTHOR]

Published
2018
Full Text
View/download PDF

17. Magnetization statics and dynamics in (Ir/Co/Pt)6 multilayers with Dzyaloshinskii–Moriya interaction.

Author

Dhiman, A. K., Gieniusz, R., Gruszecki, P., Kisielewski, J., Matczak, M., Kurant, Z., Sveklo, I., Guzowska, U., Tekielak, M., Stobiecki, F., and Maziewski, A.

Subjects
KERR magneto-optical effect, MAGNETIC force microscopy, MAGNETIZATION, MULTILAYERS, BRILLOUIN scattering, MAGNETIC anisotropy, ATOMIC number, MAGNETIZATION reversal
Abstract

Magnetic multilayers of (Ir/Co/Pt)6 with interfacial Dzyaloshinskii-Moriya interaction (IDMI) were deposited by magnetron sputtering with Co thickness d=1.8 nm. Exploiting magneto-optical Kerr effect in longitudinal mode microscopy, magnetic force microscopy, and vibrating sample magnetometry, the magnetic field-driven evolution of domain structures and magnetization hysteresis loops have been studied. The existence of weak stripe domains structure was deduced – tens micrometers size domains with in-plane "core" magnetization modulated by hundred of nanometers domains with out-of-plane magnetization. Micromagnetic simulations interpreted such magnetization distribution. Quantitative evaluation of IDMI was carried out using Brillouin light scattering (BLS) spectroscopy as the difference between Stokes and anti-Stokes peak frequencies Δf. Due to the additive nature of IDMI, the asymmetric combination of Ir and Pt covers led to large values of effective IDMI energy density Deff. It was found that Stokes and anti-Stokes frequencies as well as Δf, measured as a function of in-plane applied magnetic field, show hysteresis. These results are explained under the consideration of the influence of IDMI on the dynamics of the in-plane magnetized "core" with weak stripe domains. [ABSTRACT FROM AUTHOR]

Published
2022
Full Text
View/download PDF

19. Magnetic phases in Pt/Co/Pt films induced by single and multiple femtosecond laser pulses.

Author

Kisielewski, J., Kurant, Z., Sveklo, I., Tekielak, M., Wawro, A., and Maziewski, A.

Subjects
*FEMTOSECOND lasers research, *LASER pulses, *LASER beams, *LASER research, *ENERGY density
Abstract

Ultrathin Pt/Co/Pt trilayers with initial in-plane magnetization were irradiated with femtosecond laser pulses. In this way, an irreversible structural modification was introduced, which resulted in the creation of numerous pulse fluence-dependent magnetic phases. This was particularly true with the out-of-plane magnetization state, which exhibited a submicrometer domain structure. This effect was studied in a broad range of pulse fluences up to the point of ablation of the metallic films. In addition to this single-pulse experiment, multiple exposure spots were also investigated, which exhibited an extended area of out-of-plane magnetization phases and a decreased damage threshold. Using a double exposure with partially overlapped spots, a two-dimensional diagram of the magnetic phases as a function of the two energy densities was built, which showed a strong inequality between the first and second incoming pulses. [ABSTRACT FROM AUTHOR]

Published
2016
Full Text
View/download PDF

21. Irreversible modification of magnetic properties of Pt/Co/Pt ultrathin films by femtosecond laser pulses.

Author

Kisielewski, J., Dobrogowski, W., Kurant, Z., Stupakiewicz, A., Tekielak, M., Kirilyuk, A., Kimel, A., Rasing, Th., Baczewski, L. T., Wawro, A., Balin, K., Szade, J., and Maziewski, A.

Subjects
*COBALT platinum films, *FEMTOSECOND lasers research, *SPIN crossover, *KERR magneto-optical effect, *MAGNETIC properties, *MAGNETIZATION
Abstract

Annealing ultrathin Pt/Co/Pt films with single femtosecond laser pulses leads to irreversible spin-reorientation transitions and an amplification of the magneto-optical Kerr rotation. The effect was studied as a function of the Co thickness and the pulse fluence, revealing two-dimensional diagrams of magnetic properties. While increasing the fluence, the creation of two branches of the out-of-plane magnetization state was found. [ABSTRACT FROM AUTHOR]

Published
2014
Full Text
View/download PDF

22. Comparative analysis of ferroelectric domain statistics via nonlinear diffraction in random nonlinear materials

Author

Wang, B, Switkowski, Krzysztof, Cojocaru, Crina, Roppo, V., Sheng, Yan, Scalora, Michael, Kisielewski, J, Pawlak, D, Vilaseca, Ramon, Akhouayri, H., Krolikowski, Wieslaw, Trull, Jose, Wang, B, Switkowski, Krzysztof, Cojocaru, Crina, Roppo, V., Sheng, Yan, Scalora, Michael, Kisielewski, J, Pawlak, D, Vilaseca, Ramon, Akhouayri, H., Krolikowski, Wieslaw, and Trull, Jose

Abstract

We present an indirect, non-destructive optical method for domain statistic characterization in disordered nonlinear crystals having homogeneous refractive index and spatially random distribution of ferroelectric domains. This method relies on the analysis of the wave-dependent spatial distribution of the second harmonic, in the plane perpendicular to the optical axis in combination with numerical simulations. We apply this technique to the characterization of two different media, Calcium Barium Niobate and Strontium Barium Niobate, with drastically different statistical distributions of ferroelectric domains.

Published
2018

23. Comparative analysis of ferroelectric domain statistics via nonlinear diffraction in random nonlinear materials

Author

Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. DONLL - Dinàmica no Lineal, Òptica no Lineal i Làsers, Wang, Bin, Switowski, K, Cojocaru, Crina, Roppo, V, Sheng, Yan, Escalora, M., Kisielewski, J., Pawlak, D., Vilaseca Alavedra, Ramon, Akhouayri, H., Krolikowski, Wieslaw, Trull Silvestre, José Francisco, Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. DONLL - Dinàmica no Lineal, Òptica no Lineal i Làsers, Wang, Bin, Switowski, K, Cojocaru, Crina, Roppo, V, Sheng, Yan, Escalora, M., Kisielewski, J., Pawlak, D., Vilaseca Alavedra, Ramon, Akhouayri, H., Krolikowski, Wieslaw, and Trull Silvestre, José Francisco

Abstract

© 2018 [Optical Society of America]. Users may use, reuse, and build upon the article, or use the article for text or data mining, so long as such uses are for non-commercial purposes and appropriate attribution is maintained. All other rights are reserved., We present an indirect, non-destructive optical method for domain statistic characterization in disordered nonlinear crystals having homogeneous refractive index and spatially random distribution of ferroelectric domains. This method relies on the analysis of the wave-dependent spatial distribution of the second harmonic, in the plane perpendicular to the optical axis in combination with numerical simulations. We apply this technique to the characterization of two different media, Calcium Barium Niobate and Strontium Barium Niobate, with drastically different statistical distributions of ferroelectric domains., Peer Reviewed, Postprint (published version)

Published
2018

27. Driving properties of magnetic nanostructures

Author

Mazalski, P., Kisielewski, J., Jakubowski, M., Kurant, Z., Tahir, N., Bali, R., Wojciechowski, T., Sveklo, I., Fassbender, J., Wawro, A., Spiridis, N., and Maziewski, A.

Abstract

No abstract available.

Published
2016

30. A deeper insight into (Lu,Y)AG:Pr scintillator crystals

Author

Drozdowski, W., primary, Wojtowicz, A.J., additional, Brylew, K., additional, Łachmański, W., additional, Talik, E., additional, Szubka, M., additional, Kusz, J., additional, Guzik, A., additional, Balin, K., additional, Kisielewski, J., additional, Świrkowicz, M., additional, and Pajączkowska, A., additional

Published
2017
Full Text
View/download PDF

32. Ultrathin films: Light and ions irradiations induced changes of magnetic properties

Author

Kisielewski, J., Kisielewski, M., Kurant, Z., Mazalski, P., Stupakiewicz, A., Sveklo, I., Tekielak, M., Wawro, A., Fassbender, J., and Maziewski, A.

Subjects
Light and ions irradiations induced changes of magnetic properties [Ultrathin films]
Abstract

When decreasing ultrathin film thickness d, an increase of the perpendicular magnetic anisotropy (PMA) occurs, resulting in the magnetization reorientation phase transition (RPT) from the in-plane to out-of-plane magnetization state below the critical thickness dRPT. The results of combined experimental, analytical, and micromagnetic simulations studies on the evolution of magnetization states and processes in ultrathin films and multilayered systems [1] will be presented. Possibilities of tuning the magnetic domain sizes in a broad range (of several orders of magnitude) by changing the geometrical parameters of the nanostructure, as well as by an applied external magnetic field will be discussed. Transitions between two- and three-dimensional magnetization distributions will be shown. As a result of the ion irradiation of the metallic ultrathin films, a decrease of PMA was usually reported [2]. Contrariwise, Ga+ ion irradiation driven creation of the out-of-plane magnetization states, dependent on ion fluence, have been found [3]. Similarly, femtosecond light pulses of high energy density may also induce irreversible enhancement of PMA [4], while low energy density pulses can be used to trigger the magnetization oscillations, via reversible thermal changes of the magnetic anisotropy [5]. 1. A. Maziewski, J. Fassbender, J. Kisielewski, M. Kisielewski, Z. Kurant, P. Mazalski, F. Stobiecki, A. Stupakiewicz, I.Sveklo, M.Tekielak, A.Wawro, and V. Zablotskii, Magnetization states and magnetization processes in nanostructures: From a single layer to multilayers, Phys. Status Solidi A, 211, 1005 (2014). 2. H. Bernas (Ed.), Materials Science with Ion Beams, Vol. 116 (Springer-Verlag, Berlin, Berlin, 2010). 3. A. Maziewski, P. Mazalski, Z. Kurant, M. O. Liedke, J. McCord, J. Fassbender, J. Ferré, A. Mougin, A. Wawro, L. T. Baczewski, A. Rogalev, F. Wilhelm, and T. Gemming, Tailoring of magnetism in Pt/Co/Pt ultrathin films by ion irradiation, Phys. Rev. B 85, 054427 (2012). 4. J. Kisielewski, W. Dobrogowski, Z. Kurant, A. Stupakiewicz, M. Tekielak, A. Kirilyuk, A. Kimel, Th. Rasing, L. T.Baczewski, A. Wawro, K. Balin, J. Szade, and A. Maziewski, Irreversible modification of magnetic properties of Pt/Co/Pt ultrathin films by femtosecond laser pulses, Journal of Applied Physics 115, 053906 (2014), 5. J. Kisielewski, A. Kirilyuk, A. Stupakiewicz, A. Maziewski, A. Kimel, Th. Rasing, L. T. Baczewski, and A. Wawro, Laser-induced manipulation of magnetic anisotropy and magnetization precession in an ultrathin cobalt wedge, Phys. Rev. B 85 (2012) 184429.

Published
2015

33. Magnetization states and magnetization processes in nanostructures: From a single layer to multilayers

Author

Maziewski, A., Fassbender, J., Kisielewski, J., Kisielewski, M., Kurant, Z., Mazalski, P., Stobiecki, F., Stupakiewicz, A., Sveklo, I., Tekielak, M., Wawro, A., and Zablotskii, V.

Subjects
Condensed Matter::Materials Science, magnetic anisotropy, magnetic ultrathin films and multilayers, light and ions irradiation effects, magnetic ordering, magnetic domains
Abstract

The results of combined (experimental, analytical, and micromagnetic simulations) studies on the evolution of magnetization states and processes in ultrathin films and multilayered systems are presented. We show ways to manipulate magnetization distributions in ultrathin magnetic single or multilayers by tuning: the thickness of the magnetic layer, the thickness of either the non-magnetic cap or spacer layer, the magnetic anisotropy, and the geometrical constrictions of the system. In ultrathin magnetic films, both the magnetization distribution and the critical thickness of the magnetization reorientation phase transition (RPT) between perpendicular and in-plane states can be also controlled by post-growth treatments, e.g., by either ion or light irradiation. By changing the geometrical parameters of the nanostructure, as well as by an applied external magnetic field, one can tune magnetic domain sizes in a giant range (of a few orders of magnitude) and induce the RPT. Transitions between two- and three-dimensional magnetization distributions are discussed. The authors present possibilities of the engineering of magnetic properties (e.g. magnetic anisotropy and coercivity field) of nanostructures during deposition processes and post growth treatments, e.g. by ion irradiation and laser annealing. Magnetization distributions in single ultrathin layer and multilayers have been studied both experimentally (using Co films sandwiched between Au, Pt or Mo layers) and theoretically. These huge distribution changes, driven by nanostructure geometry or magnetic field, are shown.

Published
2014

35. Ion bombardment and light irradiation driven modifications of magnetic nanostructures

Author

Maziewski, A., Kisielewski, J., Kurant, Z., Mazalski, P., Sveklo, I., Tahir, N., Jakubowski, M., Wojciechowski, T., Wawro, A., (0000-0003-3893-9630) Fassbender, J., Stobiecki, F., Maziewski, A., Kisielewski, J., Kurant, Z., Mazalski, P., Sveklo, I., Tahir, N., Jakubowski, M., Wojciechowski, T., Wawro, A., (0000-0003-3893-9630) Fassbender, J., and Stobiecki, F.

Abstract

Much attention is paid to magnetic nanostructures due to their intrigiung properties and different applications. Appearance of perpendicular magnetic anisotropy (PMA) when a magnetic layer thickness is decreased and a giant magneto-resistance effect are the most interesting effects. Tuning the magnetic domain sizes in a broad range (several orders of magnitude) by changing PMA, the geometrical parameters of the nanostructure, as well as by an applied external magnetic field is observed, see the review [1]. Patterned nanostructures with PMA are prospective for e.g.: mass memories together with magnetic ratchet memories, magnetic field sensors, spin wave applications. A decrease of PMA as a result of the ion irradiation of the metallic ultrathin films, has been usually reported [2]. However we have recently shown that, Ga+ ion irradiation drives creation of the out-of-plane magnetization states, dependent on the ion fluence [3,4]. Irradiation with Ga+, Ar+, He+ ions results in an increase of magnetooptical effects and changes the coercivity field. We have also found that femtosecond light pulses induce: (i) reversible PMA changes which can be used to trigger magnetization oscillations [4] and (ii) irreversible PMA modifications [5] due to creation of out-of-plane magnetization states for low and high light power densities, respectively. Ion/light irradiation affecting magnetic and magnetooptical properties of nanostructures is a promising approach for new patterning purposes. Such desired modifications can be realized with fluence/energy densities lower than that reqired for the nanostructure surface etching. Moreover, using e.g. focused ion beam technique, lateral patterning can be performed with a nanometer precision. New metamaterials such as magnonic and magnetophotonic crystals or controllable transport of magnetic beads can be created in this way. Acknowledgements This work was supported by: National Science Center in Poland under the project HARMONIA Nr 2012/06

Published
2015

36. 33000 photons per MeV from mixed (Lu0.75Y0.25)3Al5O12:Pr scintillator crystals

Author

Drozdowski, W. (author), Brylew, K. (author), Wojtowicz, A.J. (author), Kisielewski, J. (author), Swirkowicz, M. (author), Lukasiewicz, T. (author), De Haas, J.T.M. (author), Dorenbos, P. (author), Drozdowski, W. (author), Brylew, K. (author), Wojtowicz, A.J. (author), Kisielewski, J. (author), Swirkowicz, M. (author), Lukasiewicz, T. (author), De Haas, J.T.M. (author), and Dorenbos, P. (author)

Abstract

(LuxY1-x)3Al5O12:Pr (x = 0.25, 0.50, 0.75) crystals have been grown by the Czochralski method and their scintillation properties have been examined. Compared to the well-respected LuAG:Pr scintillator, which has so extensively been studied in the recent years, the new mixed LuYAG:Pr crystals display markedly higher light yields, regardless of the value of x. In particular, (Lu0.75Y0.25)3Al5O12:0.2%Pr characterized by a yield of 33000 ph/MeV, an energy resolution of 4.4% (at 662 keV), and a density of 6.2 g/cm3, seems to be an ideal candidate to supercede Lu3Al5O12:0.2%Pr (19000 ph/MeV, 4.6%, 6.7 g/cm3) in various applications. The observed enhancement of light output following the partial substitution of lutetium by yttrium is most probably related to some specific differences in distributions of shallow traps in particular materials., RST/Radiation, Science and Technology, Applied Sciences

Published
2014
Full Text
View/download PDF

38. Controlling the magnetic anisotropy in ultrathin metallic films

Author

Rasing, T.H.M., Maziewski, A., Kirilyuk, A.I., Kimel, A.V., Kisielewski, J., Rasing, T.H.M., Maziewski, A., Kirilyuk, A.I., Kimel, A.V., and Kisielewski, J.

Abstract

Radboud Universiteit Nijmegen, 4 juli 2013, Promotores : Rasing, T.H.M., Maziewski, A., Kirilyuk, A.I. Co-promotor : Kimel, A.V., Contains fulltext : 111124.pdf (publisher's version ) (Open Access)

Published
2013

46. The Czochralski Growth and Characterization of SrLaGa3O7:Ho(3+) Single Crystals

Author

INSTITUTE OF ELECTRONIC MATERIALS TECHNOLOGY WARSAW (POLAND), Pracka, I., Malinowski, M., Swirkowicz, M., Kisielewski, J., Bajor, A., INSTITUTE OF ELECTRONIC MATERIALS TECHNOLOGY WARSAW (POLAND), Pracka, I., Malinowski, M., Swirkowicz, M., Kisielewski, J., and Bajor, A.

Abstract

Rare - earth (Nd, Pr, Dy) doped SrLaGa3O7 single crystals are promising laser materials. Also crystals doped with Ho(3+) ions could be used as efficient laser in visible and near infrared regions. Laser materials, generating in visible and infrared regions, can be used for optical data recording in microphotolithography and in medicine. SrLaGa3O7 single crystals doped with 0.3, 1.5 and 2 at % of Ho(3+), respectively were grown by the Czochralski method with use of iridium crucible and afterheater. According to EPMA measurements distribution coefficient of Ho(3+) in SrLaGa3O7 was estimated to be K approx. 0.22. Optical absorption spectra in visible and infrared regions were measured at 300 K and 12 K, respectively. Optical quality of single crystals was checked by the use of computerized imaging spectropolarimeter and polariscopic measurements. Temperature dependence of capacitance and conductivity for different dopant concentrations were also measured., Prepared in cooperation with the Polish Society for Crystal Growth, SPIE-The International Society for Optical Engineering in association with SPIE Poland Chapter; Inst. of Microelectronics and Optoelectronics, Warsaw, Poland. Pub. in Proc. SPIE, Vol. 4412 pp375-379, 2001. This article is from ADA399287 International Conference on Solid State Crystals 2000: Growth, Characterization, and Applications of Single Crystals Held in Zakopane, Poland on 9-12 October 2000

Published
2001

Catalog

Books, media, physical & digital resources
See catalog results