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Ing. Oldřich Schneeweiss, DrSc.
Pozice: vedoucí
Skupiny: Víceškálové modelování a měření fyzikálních vlastností (CEITEC ÚFM), Skupina elektrických a magnetických vlastností
Místnosti: 315, Mössbauer.lab., 120
Telefonní čísla: +420 532 290 434, +420 532 290 311, +420 532 290 312
E-mail: schneew@DELETE-THIS.CZ@DELETE-THIS.COMipm.cz.COM
Projekty
Nanočástice na bázi železa a oxidů železa pro magnetické separační procesy
Výzkumné centrum práškových nanonateriálů
Struktura, elektrické a magnetické vlastnosti nanokrystalických materiálů složených z uhlíku a 3d transitivních kovů
Atomové uspořádání na površích a rozhraních slitin 3d kovů
Povrchy a rozhraní v konstrukčních materiálech - aplikace moderních technologií a počítačového modelování
Publikace:
2017

Q1 PUBLICATION:
Oldřich Schneeweiss, Martin Friák, Marie Dudová, David Holec, Mojmír Šob, Dominik Kriegner, Václav Holý, Přemysl Beran, Easo P. George, Jörg Neugebauer, and Antonín Dlouhý,
Magnetic properties of the CrMnFeCoNi high-entropy alloy,
Physical Review B 96 (2017) 014437-1 - 014437-13.

Description
We present experimental data showing that the equiatomic CrMnFeCoNi high-entropy alloy undergoes two magnetic transformations at temperatures below 100 K while maintaining its fcc structure down to 3 K. The first transition, paramagnetic to spin glass, was detected at 93 K and the second transition of the ferromagnetic type occurred at 38 K. Field-assisted cooling below 38 K resulted in a systematic vertical shift of the hysteresis curves. Strength and direction of the associated magnetization bias was proportional to the strength and direction of the cooling field and shows a linear dependence with a slope of 0.006 +/- 0.001 emu/T. The local magnetic moments of individual atoms in the CrMnFeCoNi quinary fcc random solid solution were investigated by ab initio (electronic density functional theory) calculations. Results of the numerical analysis suggest that, irrespective of the initial configuration of local magnetic moments, the magnetic moments associated with Cr atoms align antiferromagnetically with respect to a cumulative magnetic moment of their first coordination shell. The ab initio calculations further showed that the magnetic moments of Fe and Mn atoms remain strong (between 1.5 and 2 Bohr magneton), while the local moments of Ni atoms effectively vanish. These results indicate that interactions of Mn- and/or Fe-located moments with the surrounding magnetic structure account for the observed macroscopic magnetization bias.

2015
2014
2010
O. Schneeweiss, B. David, T. Žák, J. Filip, J. Tuček, R. Zbořil:
Magnetic interactions between nanoparticles formed during calcination of ferrihydrite,
Acta Physica Polonica A 118 (2010) 749-750
2007
O. Schneeweiss, B. David, T. Žák, R. Zbořil, and M. Mashlan:
Nanocrystalline Fe–Ni and Fe–Co samples prepared by powder processing
J. Magn. Magn. Mater., 310 (2007) e858–e860
2006
B. David, M. Pizúrová, O. Schneeweiss, P. Bezdička, M. Klementová, J. Filip, R. Alexandrescu, F. Dumitrache, C.T. Fleaca, I. Voicu, and I. Morjan:
Multi-walled carbon nanotubes formed by condensed-phase conversions of Fe-C-based nanopowder in vacuum
Czech. J. Phys. 56 2006 E51-E61
B. David, O. Schneeweiss, N. Pizúrová, M. Klementová, P. Bezdička, R. Alexandrescu, F. Dumitrache, and I. Morjan:
Fe3C nanopowder synthesized by laser pyrolysis and its annealing behaviour
Surf. Interf. Analysis 38, 2006 482-485
2005
J. Čermák, I. Stloukal and O. Schneeweiss: Short-Circuit Diffusion of 99Mo in Partly Crystallized Fe76Mo8B15Cu1, Fe40Ni40B20 and Fe80B20 Alloys. Proceedings NANO '05, Brno, Czech Republic, November 8-10, 2005, p. 302.
B. David, M. Pizúrová, O. Schneeweiss, P. Bezdička, R. Alexandrescu, I. Morjan, A. Crunteanu, and I. Voicu:
Magnetic properties of iron/graphite core-shell nanoparticles prepared by annealing of Fe-G-N-based nanocomposite
J. Magn. Magn. Mater. 290 (2005) 179-182
2004
B. David, M. Pizúrová, O. Schneeweiss, P. Bezdička, I. Morjan, and R. Alexandrescu:
Preparation of iron/graphite core-shell structured nanoparticles
J. Alloys Compd. 378 (2004) 112-116
2002
O. Schneeweiss, Y. Jirásková, T. Žák, J. Šebek, S.F. Lin, and X.K. Yao:
Preparation and properties of FeNi-Mg/MgO nanocomposite
Czech. J. Phys. 52 (2002) 167–170
O. Schneeweiss, Y. Jirásková, J. Čermák and P. Lejček: Atomic Ordering at Grain Boundaries in Fe-Si and Fe-Al Alloys. Proceedings of International Conference on the Applications of the Mössbauer Effect (ICAME2001), Kluwer, Dordrecht, 2002, 571.
Y. Jirásková, M. Svoboda, O. Schneeweiss, and T. Žák:
Structural properties of austenitic stainless steel in the initial state and after rf plasma nitriding
Czech. J. Phys. 52 (2002) A61–A64
2001
O. Schneeweiss, Y. Jirásková, J. Čermák and P. Lejček: Comparison of Site Preferences of 57Co at Grain Boundaries in Fe-Si and Fe-Al Alloys. METAL 2001 - 10th International Metallurgical & Material Conference, Ostrava, Czech Republic, May 15-17 2001, CD-ROM.
2000
Informační leták
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Poslední změna
19. 09. 2017