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Matej Badin

Publications and source records attributed to Matej Badin.

4 recordsLinked to original sources

Non-adiabatic corrections to chiral charge pumping in topological nodal semimetals

Studying many-body versions of Landau-Zener-like problems of non-interacting electrons in the Slater formalism for several $k \cdot p$ models representing Weyl and Dirac semimetals, we systematically include non-adiabatic corrections to a quantum limit of chiral charge pumping in these models. In this paper, we show that relative homotopy invariant [Sun et al., Phys. Rev. Lett. 121, 106402 (2018)] and Euler class invariant [Bouhon et al., Nat. Phys. 16, 1137 (2020)] non-trivially manifest in the non-adiabatic corrections to the quantum limit of chiral charge pumping. These corrections could affect conductivity channels connected with the presence of chiral anomaly. Moreover, we show that, for non-symmorphic systems, this contribution is sensitive to the direction of the applied magnetic field (in respect to the so-called non-symmorphic nodal loop), suggesting that the conjectured direction-selective chiral anomaly in non-symmorphic systems [Bzdušek et al., Nature (London) 538, 75 (2016)] could lead to a strongly anisotropic longitudinal magnetoresistance. The presented approach can be easily applied to other $k \cdot p$ or tight-binding models.

cond-mat.mes-hall

Nucleating a Different Coordination in a Crystal under Pressure: A Study of the B1-B2 Transition in NaCl by Metadynamics

Here we propose an NPT metadynamics simulation scheme for pressure-induced structural phase transitions, using coordination number and volume as collective variables, and apply it to the reconstructive structural transformation $B1$-$B2$ in NaCl. By studying systems with size up to 64 000 atoms we reach a regime beyond collective mechanism and observe transformations proceeding via nucleation and growth. We also reveal the crossover of the transition mechanism from Buerger-like for smaller systems to Watanabe-Tolédano for larger ones. The scheme is likely to be applicable to a broader class of pressure-induced structural transitions, allowing study of complex nucleation effects and bringing simulations closer to realistic conditions.

cond-mat.mtrl-sci

The International Young Physicists' Tournament 2017

In July 2017, National University of Singapore hosted the 30th International Young Physicists' Tournament (IYPT) with symbolic participation of $30$ competing teams. IYPT is a modern scientific competition for teams of high school students, also known as Physics World Cup. Here we present a brief report from this years competition with a concise list of problems solved by participating teams. For one of the problems, Torsion gyroscope, we also bring a glimpse into its theoretical and experimental solution.

physics.ed-ph

Gee-Haw Whammy Diddle

Gee-Haw Whammy Diddle is a seemingly simple mechanical toy consisting of a wooden stick and a second stick that is made up of a series of notches with a propeller at its end. When the wooden stick is pulled over the notches, the propeller starts to rotate. In spite of its simplicity, physical principles governing the motion of the stick and the propeller are rather complicated and interesting. Here we provide a thorough analysis of the system and parameters influencing the motion. We show that contrary to the results published on this topic so far, neither elliptic motion of the stick nor frequency synchronization is needed for starting the motion of the propeller.

physics.class-ph