Browsing by Author "Ivashko, Oleh"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- ItemEngineering a pure Dirac regime in ZrTe5(Amsterdam : SciPost Foundation, 2023) Facio, Jorge I.; Nocerino, Elisabetta; Fulga, Ion Cosma; Wawrzynczak, Rafal; Brown, Joanna; Gu, Genda; Li, Qiang; Mansson, Martin; Sassa, Yasmine; Ivashko, Oleh; von Zimmermann, Martin; Mende, Felix; Gooth, Johannes; Galeski, Stanislaw; van den Brink, Jeroen; Meng, TobiasReal-world topological semimetals typically exhibit Dirac and Weyl nodes that coexist with trivial Fermi pockets. This tends to mask the physics of the relativistic quasiparticles. Using the example of ZrTe5, we show that strain provides a powerful tool for in-situ tuning of the band structure such that all trivial pockets are pushed far away from the Fermi energy, but only for a certain range of Van der Waals gaps. Our results naturally reconcile contradicting reports on the presence or absence of additional pockets in ZrTe5, and provide a clear map of where to find a pure three-dimensional Dirac semimetallic phase in the structural parameter space of the material.
- ItemIn situ correlation between metastable phase-transformation mechanism and kinetics in a metallic glass([London] : Nature Publishing Group, 2021) Orava, Jiri; Balachandran, Shanoob; Han, Xiaoliang; Shuleshova, Olga; Nurouzi, Ebrahim; Soldatov, Ivan; Oswald, Steffen; Gutowski, Olof; Ivashko, Oleh; Dippel, Ann-Christin; v. Zimmermann, Martin; Ivanov, Yurii P.; Greer, A. Lindsay; Raabe, Dierk; Herbig, Michael; Kaban, IvanA combination of complementary high-energy X-ray diffraction, containerless solidification during electromagnetic levitation and transmission electron microscopy is used to map in situ the phase evolution in a prototype Cu-Zr-Al glass during flash-annealing imposed at a rate ranging from 102 to 103 K s−1 and during cooling from the liquid state. Such a combination of experimental techniques provides hitherto inaccessible insight into the phase-transformation mechanism and its kinetics with high temporal resolution over the entire temperature range of the existence of the supercooled liquid. On flash-annealing, most of the formed phases represent transient (metastable) states – they crystallographically conform to their equilibrium phases but the compositions, revealed by atom probe tomography, are different. It is only the B2 CuZr phase which is represented by its equilibrium composition, and its growth is facilitated by a kinetic mechanism of Al partitioning; Al-rich precipitates of less than 10 nm in a diameter are revealed. In this work, the kinetic and chemical conditions of the high propensity of the glass for the B2 phase formation are formulated, and the multi-technique approach can be applied to map phase transformations in other metallic-glass-forming systems.