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| 2. |
- Facio, Jorge, et al.
(author)
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Engineering a pure Dirac regime in ZrTe5
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In: SciPost Physics. - 2542-4653.
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Journal article (other academic/artistic)abstract
- Real-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.
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| 3. |
- Facio, Jorge I., et al.
(author)
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Engineering a pure Dirac regime in ZrTe5
- 2023
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In: SciPost Physics. - : Stichting SciPost. - 2542-4653. ; 14:4
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Journal article (peer-reviewed)abstract
- Real-world topological semimetals typically exhibit Dirac and Weyl nodes that coexist with trivial Fermi pockets. This tends to mask the physics of the relativistic quasiparti-cles. 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.
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| 4. |
- Könye, Viktor, et al.
(author)
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Chirality flip of Weyl nodes and its manifestation in strained MoTe2
- 2021
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In: Physical Review Research. - 2643-1564. ; 3:4
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Journal article (peer-reviewed)abstract
- Due to their topological charge, or chirality, the Weyl cones present in topological semimetals are considered robust against arbitrary perturbations. One well-understood exception to this robustness is the pairwise creation or annihilation of Weyl cones, which involves the overlap in energy and momentum of two oppositely charged nodes. Here we show that the topological charge can in fact change sign, in a process that involves the merging of not two, but three Weyl nodes. This is facilitated by the presence of rotation and time-reversal symmetries, which constrain the relative positions of Weyl cones in momentum space. We analyze the chirality flip process, showing that transport properties distinguish it from the conventional, double Weyl merging. Moreover, we predict that the chirality flip occurs in MoTe2, where experimentally accessible strain leads to the merging of three Weyl cones close to the Fermi level. Our work sets the stage to further investigate and observe such chirality flipping processes in different topological materials.
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| 5. |
- Yadav, Ravi, et al.
(author)
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Heavy-mass magnetic modes in pyrochlore iridates due to dominant Dzyaloshinskii-Moriya interaction
- 2018
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In: Physical Review Materials. - 2475-9953. ; 2:7
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Journal article (peer-reviewed)abstract
- Materials with strong spin-orbit interactions are presently a main target in the search for systems with novel magnetic properties. Magnetic anisotropies can be very large in such compounds, ranging from strongly frustrated Kitaev exchange and the associated spin-liquid states in honeycomb iridates to robust antisymmetric couplings in square-lattice Sr2IrO4. Here we predict from ab initio quantum chemistry calculations that another highly unusual regime is realized in pyrochlore iridium oxides: the isotropic nearest-neighbor Heisenberg term can vanish while the antisymmetric Dzyaloshinskii-Moriya interaction reaches values as large as 5 meV, a result which challenges common notions and existing phenomenological models of magnetic superexchange. The resulting spin-excitation spectra reveal a very flat magnon dispersion in the Nd- and Tb-based pyrochlore iridates, suggesting the possibility of using these modes to store magnetic information. Indeed, the magnetization dynamics indicates that these modes are unable to propagate out of the excitation region. Although most of the results presented here are predictions of exotic magnetic states based on first-principles theory, we make connections to observations and establish the accuracy of our approach by reproducing experimental data for Sm2Ir2O4.
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