A5079176743- Topological Materials and Phenomena
- Advanced Condensed Matter Physics
- Physics of Superconductivity and Magnetism
- Graphene research and applications
- Quantum many-body systems
- Quantum and electron transport phenomena
- Quantum, superfluid, helium dynamics
- Cold Atom Physics and Bose-Einstein Condensates
- 2D Materials and Applications
- Quantum Mechanics and Non-Hermitian Physics
- Rare-earth and actinide compounds
- Iron-based superconductors research
- Electronic and Structural Properties of Oxides
- Magnetic and transport properties of perovskites and related materials
- Quantum chaos and dynamical systems
- Diamond and Carbon-based Materials Research
- Magnetic properties of thin films
- Theoretical and Computational Physics
- Atomic and Subatomic Physics Research
- Advanced Chemical Physics Studies
- Neural Networks and Applications
- Algebraic structures and combinatorial models
- Quantum Computing Algorithms and Architecture
- Advanced Materials Characterization Techniques
- Electron and X-Ray Spectroscopy Techniques
University of Zurich
2016-2025
Princeton University
2014-2024
Lawrence Berkeley National Laboratory
2024
ETH Zurich
2013-2014
Paul Scherrer Institute
2010-2014
Leibniz Institute for Solid State and Materials Research
2014
Swiss Light Source
2012
RIKEN Center for Emergent Matter Science
2010
TU Dresden
2008
We present a simple prescription to flatten isolated Bloch bands with nonzero Chern number. first show that approximate flattening of number is possible by tuning ratios nearest-neighbor and next-nearest-neighbor hoppings in the Haldane model and, similarly, chiral-π-flux square lattice model. Then we perfect can be attained further range decrease exponentially distance. Finally, add interactions exact diagonalization results for small system at 1/3 filling support (i) existence spectral...
Abstract Topological semimetals can support one-dimensional Fermi lines or zero-dimensional Weyl points in momentum space, where the valence and conduction bands touch. While degeneracy are robust against any perturbation that preserves translational symmetry, nodal require protection by additional crystalline symmetries such as mirror reflection. Here we report, based on a systematic theoretical study detailed experimental characterization, existence of topological nodal-line states...
Abstract Weyl semimetals provide the realization of fermions in solid-state physics. Among all physical phenomena that are enabled by semimetals, chiral anomaly is most unusual one. Here, we report signatures magneto-transport measurements on first semimetal TaAs. We show negative magnetoresistance under parallel electric and magnetic fields, is, unlike metals whose resistivity increases an external field, observe our high mobility TaAs samples become more conductive as a field applied along...
Three-dimensional topological (crystalline) insulators are materials with an insulating bulk, but conducting surface states which topologically protected by time-reversal (or spatial) symmetries. Here, we extend the notion of three-dimensional to systems that host no gapless states, exhibit hinge states. Their character is spatio-temporal symmetries, present two cases: (1) Chiral higher-order combination and a four-fold rotation symmetry. chiral modes bulk topology $\mathbb{Z}_2$-classified....
Weyl semimetals are expected to open up new horizons in physics and materials science because they provide the first realization of fermions exhibit protected Fermi arc surface states. However, had been found be extremely rare nature. Recently, a family compounds, consisting tantalum arsenide, phosphide (TaP), niobium phosphide, was predicted as semimetal candidates. We experimentally realize state TaP. Using photoemission spectroscopy, we directly observe fermion cones nodes bulk, arcs on...
We identify a Weyl semimetal state in an inversion breaking, stoichiometric compound strontium silicide, SrSi$_2$, with many new and novel properties that are distinct from the TaAs family. theoretically show SrSi$_2$ is even without spin-orbit coupling that, after inclusion of coupling, two fermions stick together forming exotic double fermion quadratic dispersions higher chiral topological charge 2. Moreover, we find nodes opposite charges located at different energies due to absence...
A topological nodal-line semimetal is a state of matter with one-dimensional bulk nodal lines and two-dimensional so-called drumhead surface bands. Based on first-principles calculations an effective $\mathbit{k}\ifmmode\cdot\else\textperiodcentered\fi{}\mathbit{p}$ model, we theoretically propose the existence fermions in ternary transition-metal chalcogenide ${\mathrm{TlTaSe}}_{2}$. The noncentrosymmetric structure strong spin-orbit coupling give rise to spinful states which are protected...
Fractional Chern insulators are theoretically predicted states of electronic matter with emergent topological order. They exhibit the same universal properties as fractional quantum Hall effect, but dispose need to apply a strong magnetic field. However, despite intense theoretical work, an experimental realization for these exotic is still lacking. Here we show that doped graphene turns into insulator, when irradiated high-intensity circularly polarized light. We derive effective steady...
Artificial neural networks have been recently introduced as a general ansatz to compactly represent many- body wave functions. In conjunction with Variational Monte Carlo, this has applied find Hamil- tonian ground states and their energies. Here we provide extensions of method study properties ex- cited states, central task in several many-body quantum calculations. First, give prescription that allows target eigenstates (nonlocal) symmetry the Hamiltonian. Second, an algorithm compute...
In quantum field theory, Weyl fermions are relativistic particles that travel at the speed of light and strictly obey celebrated Lorentz symmetry. Their low-energy condensed matter analogs semimetals, which conductors whose electronic excitations mimic fermion equation motion. Although traditional (type I) emergent observed in TaAs still approximately respect symmetry, recently, so-called type II semimetal has been proposed, where quasiparticles break symmetry so strongly they cannot be...
The use of artificial neural networks to represent quantum wave-functions has recently attracted interest as a way solve complex many-body problems. potential these variational parameterizations been supported by analytical and numerical evidence in controlled benchmarks. While approaching the end early research phase this field, it becomes increasingly important show how neural-network states perform for models physical problems that constitute clear open challenge other computational...
The recent discovery of AV_{3}Sb_{5} (A=K,Rb,Cs) has uncovered an intriguing arena for exotic Fermi surface instabilities in a kagome metal. Among them, superconductivity is found the vicinity multiple van Hove singularities, exhibiting indications unconventional pairing. We show that sublattice interference mechanism central to understanding formation Starting from appropriately chosen minimal tight-binding model with singularities close level AV_{3}Sb_{5}, we provide random phase...
We theoretically study the quench dynamics for an isolated Heisenberg spin chain with a random on-site magnetic field, which is one of paradigmatic models many-body localization transition. use time-dependent variational principle as applied to matrix product states, allows us controllably chains length up $L=100$ spins, i.e., much larger than $L\ensuremath{\simeq}20$ that can be treated via exact diagonalization. For analysis data, three complementary approaches are used: (i) determination...
Weyl semimetals are novel topological conductors that host fermions as emergent quasiparticles. In this Rapid Communication, we propose a new type of semimetal state breaks both time-reversal symmetry and inversion in the $R\mathrm{AlGe}$ ($R=\mathrm{rare}\ensuremath{-}\mathrm{earth}$) family. Compared to previous predictions magnetic candidates, prediction nodes is more robust less dependent on details magnetism because generated already by breaking ferromagnetism acts simple Zeeman...
Magnetic topological phases of quantum matter are an emerging frontier in physics and material science. Along these lines, several kagome magnets have appeared as the most promising platforms. However, magnetic nature materials presence state remains unsolved issue. Here, we explore correlations magnet Co_3Sn_2S_2. Using muon spin-rotation, present evidence for competing orders lattice this compound. Our results show that while sample exhibits out-of-plane ferromagnetic ground state,...
When electric conductors differ from their mirror image, unusual chiral transport coefficients appear that are forbidden in achiral metals, such as a non-linear response known electronic magneto-chiral anisotropy (eMChA). While signatures by symmetry allowed many without center of inversion, it reaches appreciable levels only rare cases when an exceptionally strong coupling to the itinerant electrons is present. So far, observations have been limited materials which atomic positions strongly...