Dominik Gresch


Last Name

Gresch

First Name

Dominik

ORCID

0000-0002-0150-0424

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2015 - 2019132020 - 20222
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Publications 1 - 10 of 15
  • Automated construction of symmetrized Wannier-like tight-binding models from ab initio calculations
    Item type: Journal Article
    Gresch, Dominik; Wu, QuanSheng; Winkler, Georg W.; et al. (2018)
    Physical Review Materials
  • Identifying Topological Semimetals
    Item type: Doctoral Thesis
    Gresch, Dominik (2018)
    Geometric properties of electron states in crystalline solids lead to a topological classification of materials. A remarkable consequence of this topological viewpoint is that it reveals a deep link between the bulk properties of a material and electronic states which form on its surface. This leads to unique transport properties, the most well-known example being the integer quantum Hall effect. In topological semimetals, the bulk features of interest are nodes in the band structure, where occupied and unoccupied states are not separated by an energy gap. This leads to interesting low-energy excitations, some of which are the condensed matter equivalent of fundamental particles. The Weyl Fermion for example is realized in topological semimetals, which is theoretically postulated but eludes experimental verification in high-energy physics. Crystals however do not have a continuous translational symmetry, and thus do not need to fulfill the so-called Lorentz invariance present in high-energy physics. This allows for Fermions to exist in materials which do not have a fundamental counterpart. The main topic of this thesis is the study and identification of topological semimetals. We propose a mechanism for Weyl Fermions to form under the influence of an external magnetic field. This effect could help explain the anisotropic negative magnetoresistance in transition metal dipnictides. We also study several novel topological material candidates, hosting a plethora of Weyl Fermions and topological nodal lines. In addition to studying specific material examples, we also present several tools and algorithms which enhance the process of identifying topological materials. First, we present an algorithm for evaluating the phase diagram of a system with discrete phases. This is useful in identifying topological phases, but also applicable to other fields of computational physics. Furthermore, we develop tools that simplify the creation of k·p and tight-binding models to study crystalline systems. A particular focus lies on the construction of models which preserve the crystal symmetries, since these play a crucial role in determining the topology of a material. And finally, we develop an algorithm that reliably finds and classifies topological nodal features.
  • Electronic Structure of InAs and InSb Surfaces: Density Functional Theory and Angle-Resolved Photoemission Spectroscopy
    Item type: Journal Article
    Yang, Shuyang; Schröter, Niels B.M.; Strocov, Vladimir N.; et al. (2022)
    Advanced Quantum Technologies
    The electronic structure of surfaces plays a key role in the properties of quantum devices. However, surfaces are also the most challenging to simulate and engineer. Here, the electronic structure of InAs(001), InAs(111), and InSb(110) surfaces is studied using a combination of density functional theory (DFT) and angle-resolved photoemission spectroscopy (ARPES). Large-scale first principles simulations are enabled by using DFT calculations with a machine-learned Hubbard U correction [npj Comput. Mater. 6, 180 (2020)]. To facilitate direct comparison with ARPES results, a "bulk unfolding" scheme is implemented by projecting the calculated band structure of a supercell surface slab model onto the bulk primitive cell. For all three surfaces, a good agreement is found between DFT calculations and ARPES. For InAs(001), the simulations clarify the effect of the surface reconstruction. Different reconstructions are found to produce distinctive surface states, which may be detected by ARPES with low photon energies. For InAs(111) and InSb(110), the simulations help elucidate the effect of oxidation. Owing to larger charge transfer from As to O than from Sb to O, oxidation of InAs(111) leads to significant band bending and produces an electron pocket, whereas oxidation of InSb(110) does not. The combined theoretical and experimental results may inform the design of quantum devices based on InAs and InSb semiconductors, for example, topological qubits utilizing the Majorana zero modes.
  • Type-II Weyl semimetals
    Item type: Journal Article
    Soluyanov, Alexey A.; Gresch, Dominik; Wang, Zhijun; et al. (2015)
    Nature
  • Optimizing spin-orbit splittings in InSb Majorana nanowires
    Item type: Journal Article
    Soluyanov, Alexey A.; Gresch, Dominik; Troyer, Matthias; et al. (2016)
    Physical Review B
  • MoTe2: A Type-II Weyl Topological Metal
    Item type: Journal Article
    Wang, Zhijun; Gresch, Dominik; Soluyanov, Alexey A.; et al. (2016)
    Physical Review Letters
  • Hidden Weyl points in centrosymmetric paramagnetic metals
    Item type: Journal Article
    Gresch, Dominik; Wu, QuanSheng; Winkler, Georg W.; et al. (2017)
    New Journal of Physics
    The transition metal dipnictides TaAs2, TaSb2, NbAs2 and NbSb2 have recently sparked interest for exhibiting giant magnetoresistance. While the exact nature of the magnetoresistance in these materials is still under active investigation, there are experimental results indicating that it is of the anisotropic negative variety. We study the effect of magnetic fields on the band structure topology of these materials by applying Zeeman splitting. In the absence of a magnetic field, we find that the materials are weak topological insulators, which is in agreement with previous studies. When the magnetic field is applied, we find that type-II Weyl points form. This result is found first from a symmetry argument, and then numerically for a ${\bf{k}}\cdot {\bf{p}}$ model of TaAs2 and a tight-binding model of NbSb2. This effect could be of help in the search for an explanation of the anomalous magnetoresistance in these materials.
  • Z2Pack: Numerical implementation of hybrid Wannier centers for identifying topological materials
    Item type: Journal Article
    Gresch, Dominik; Autès, Gabriel; Yazyev, Oleg V.; et al. (2017)
    Physical Review B
  • Identifying topological states in matter
    Item type: Master Thesis
    Gresch, Dominik (2015)
    The rise of topological insulators, semimetals and superconductors established the topology of the electronic band structure as a fundamental material property. Topological materials can realize exotic novel quantum states such as an integer quantum Hall state in the absence of an external magnetic field, quasiparticle states needed for topological quantum computing, and many more. The topological nature of these states makes them insensitive to small perturbations, which has profound practical consequences. Consequently, the ability to reliably identify topological states is crucial in understanding and predicting many physical effects. In this work, we propose a general approach for calculating any topological invariant, based on the charge centers of hybrid Wannier functions. The method is illustrated in the context of Chern insulators, Z 2 topological insulators and Weyl semi- metals. Most importantly, we present Z2Pack, an easy-to-use software implementing this technique. It can be used as a post-processing tool for first-principles calculations or as a standalone package for tight-binding or k.p models. The fully automated calculation of topological invariants makes Z2Pack ideally suited for both the search for topological states of matter in existing materials and the design of materials or heterostructures with desirable topology.
  • MoTe2: Weyl and Line Node Topological Metal
    Item type: Working Paper
    Wang, Zhijun; Gresch, Dominik; Soluyanov, Alexey A.; et al. (2015)
    arXiv
    Based on the ab initio calculations, we show that MoTe2, in its low-temperature orthorhombic structure characterized by an X-ray diffraction study at 100 K, realizes 4 type-II Weyl points between the N-th and N+1-th bands, where N is the total number of valence electrons per unit cell. Other WPs and nodal lines between different other bands also appear close to the Fermi level due to a complex topological band structure. We predict a series of strain-driven topological phase transitions in this compound, opening a wide range of possible experimental realizations of different topological semimetal phases. Crucially, with no strain, the number of observable surface Fermi arcs in this material is 2 - the smallest number of arcs consistent with time-reversal symmetry.
Publications 1 - 10 of 15