Andreas P. Schnyder
YOU?
Author Swipe
View article: Tunable Octdong and Spindle-Torus Fermi Surfaces in Kramers Nodal Line Metals
Tunable Octdong and Spindle-Torus Fermi Surfaces in Kramers Nodal Line Metals Open
Kramers nodal lines are doubly degenerate band crossings in achiral non-centrosymmetric crystals, arising from spin-orbit coupling and connecting time-reversal invariant momenta. When intersecting the Fermi level, they generate exotic thre…
View article: Fate of Bosonic Topological Edge Modes in the Presence of Many-Body Interactions
Fate of Bosonic Topological Edge Modes in the Presence of Many-Body Interactions Open
Many magnetic materials are predicted to exhibit bosonic topological edge modes in their excitation spectra, because of the nontrivial topology of their magnon, triplon, or other quasiparticle band structures. However, there is a discrepan…
View article: Quantum geometry and low-frequency optical conductivity of nodal planes
Quantum geometry and low-frequency optical conductivity of nodal planes Open
Nodal planes, two-dimensional symmetry-enforced band crossings, can carry a topological charge, similar to Weyl points. While the transport properties of Weyl points are well understood, those of nodal planes remain largely unexplored. The…
View article: Multiorbital character of the density wave instability in La$_4$Ni$_3$O$_{10}$
Multiorbital character of the density wave instability in La$_4$Ni$_3$O$_{10}$ Open
Ruddlesden-Popper nickelates exhibit high-temperature superconductivity closely intertwined with charge and spin density wave order. However, fundamental questions persist regarding the interplay between the associated density wave (DW) fl…
View article: Exotic superconducting states in altermagnets
Exotic superconducting states in altermagnets Open
The interplay between magnetism and superconductivity is one of the central topics of condensed matter physics, which has recently been put into new light by the discovery of altermagnets. Here, we study this interplay from a fundamental s…
View article: Topological crossings in two-dimensional altermagnets: Symmetry classification and topological responses
Topological crossings in two-dimensional altermagnets: Symmetry classification and topological responses Open
We study the symmetry requirements for topologically protected spin-polarized Dirac points in 2D altermagnets. The topology is characterized by a quantized π-Berry phase and the degeneracy is protected by spin-space group symmetries. Gappe…
View article: Weak <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="double-struck">Z</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> supertopology
Weak supertopology Open
Crystal symmetries can enforce all bands of a material to be topological, a property that is commonly referred to as “supertopology.” Here, we determine the symmetry-enforced Z2 supertopologies of nonmagnetic centrosymmetric materials with…
View article: Tunable Octdong and Spindle-Torus Fermi Surfaces in Kramers Nodal Line Metals
Tunable Octdong and Spindle-Torus Fermi Surfaces in Kramers Nodal Line Metals Open
It has recently been proposed that all achiral non-centrosymmetric crystals host so-called Kramers nodal lines, which are doubly degenerate band crossings connecting time-reversal invariant momenta in the Brillouin zone that arise due to s…
View article: Callan-Rubakov effects in topological insulators
Callan-Rubakov effects in topological insulators Open
The Callan-Rubakov effect describes monopole-catalyzed proton decay. While this effect is fundamental for quantum field theories, its experimental observation has remained far from reality. Here, we reveal a similar, but experimentally rea…
View article: Discovery of superconductivity and electron-phonon drag in the non-centrosymmetric Weyl semimetal LaRhGe3
Discovery of superconductivity and electron-phonon drag in the non-centrosymmetric Weyl semimetal LaRhGe3 Open
We present an exploration of the effect of electron-phonon coupling and broken inversion symmetry on the electronic and thermal properties of the semimetal LaRhGe3. Our transport measurements reveal evidence for electron-hole compensation …
View article: Out-of-plane bond-order phase, superconductivity, and their competition in the $t$-$J_\parallel$-$J_\perp$ model: Possible implications for bilayer nickelates
Out-of-plane bond-order phase, superconductivity, and their competition in the $t$-$J_\parallel$-$J_\perp$ model: Possible implications for bilayer nickelates Open
Almost four decades of intense research have been invested to study the physics of high-T$_c$ cuprate superconductors. The recent discovery of high-T$_c$ superconductivity in pressurized bilayer nickelates and its potential similarities wi…
View article: Magnetic coupled electronic landscape in bilayer-distorted titanium-based kagome metals
Magnetic coupled electronic landscape in bilayer-distorted titanium-based kagome metals Open
Quantum materials whose atoms are arranged on a lattice of corner-sharing triangles, i.e., the kagome lattice, have recently emerged as a captivating platform for investigating exotic correlated and topological electronic phenomena. Here, …
View article: Weak $\mathbb{Z}_2$ Supertopology
Weak $\mathbb{Z}_2$ Supertopology Open
Crystal symmetries can enforce all bands of a material to be topological, a property that is commonly referred to as ``supertopology". Here, we determine the symmetry-enforced $\mathbb{Z}_2$ supertopologies of non-magnetic centrosymmetric …
View article: Interaction-driven first-order and higher-order topological superconductivity
Interaction-driven first-order and higher-order topological superconductivity Open
We investigate topological superconductivity in the Rashba-Hubbard model, describing heavy-atom superlattice and van der Waals materials with broken inversion. We focus in particular on fillings close to the van Hove singularities, where a…
View article: Fermi surface of the chiral topological semimetal CoSi
Fermi surface of the chiral topological semimetal CoSi Open
We report a study of the Fermi surface of the chiral semimetal CoSi and its relationship to a network of multifold topological crossing points,Weyl points, and topological nodal planes in the electronic band structure. Combining quantum os…
View article: Topological responses from gapped Weyl points in 2D altermagnets
Topological responses from gapped Weyl points in 2D altermagnets Open
We study the symmetry requirements for topologically protected spin-polarized Weyl points in 2D altermagnets. The topology is characterized by a quantized $π$-Berry phase and the degeneracy is protected by spin-space group symmetries. Gapp…
View article: Spin-polarized Specular Andreev Reflections in Altermagnets
Spin-polarized Specular Andreev Reflections in Altermagnets Open
We show theoretically that specular Andreev reflection occurs stably at altermagnet--superconductor interfaces, which is a phenomenon that has previously been predicted only in a limited range of materials, such as Dirac/Weyl materials wit…
View article: Oscillating-charged Andreev Bound States and Their Appearance in UTe$_2$
Oscillating-charged Andreev Bound States and Their Appearance in UTe$_2$ Open
Surface Andreev bound states, including Majorana bound states in topological superconductors, are typically charge neutral. In this work, we demonstrate the emergence of unconventional charged Andreev bound states in a superconductor with …
View article: Crossover between electron-electron and electron-phonon mediated pairing on the kagome lattice
Crossover between electron-electron and electron-phonon mediated pairing on the kagome lattice Open
We study electron-electron and electron-phonon mediated pairing in the Holstein extended Hubbard model on the kagome lattice near the van Hove fillings, and we investigate their combined effects on electron pairing states. We find that the…
View article: Fundamental laws of chiral band crossings: Local constraints, global constraints, and topological phase diagrams
Fundamental laws of chiral band crossings: Local constraints, global constraints, and topological phase diagrams Open
We derive two fundamental laws of chiral band crossings: (i) a local constraint relating the Chern number to phase jumps of rotation eigenvalues and (ii) a global constraint determining the number of chiral crossings on rotation axes. Toge…
View article: Discovery of Superconductivity and Electron-Phonon Drag in the Non-Centrosymmetric Weyl Semimetal LaRhGe$_3$
Discovery of Superconductivity and Electron-Phonon Drag in the Non-Centrosymmetric Weyl Semimetal LaRhGe$_3$ Open
We present an exploration of the effect of electron-phonon coupling and broken inversion symmetry on the electronic and thermal properties of the semimetal LaRhGe$_3$. Our transport measurements reveal evidence for electron-hole compensati…
View article: Magnetic-coupled electronic landscape in bilayer-distorted titanium-based kagome metals
Magnetic-coupled electronic landscape in bilayer-distorted titanium-based kagome metals Open
Quantum materials whose atoms are arranged on a lattice of corner-sharing triangles, $\textit{i.e.}$, the kagome lattice, have recently emerged as a captivating platform for investigating exotic correlated and topological electronic phenom…
View article: Electronic landscape of kagome superconductors AV3Sb5 (A = K, Rb, Cs) from angle-resolved photoemission spectroscopy
Electronic landscape of kagome superconductors AV3Sb5 (A = K, Rb, Cs) from angle-resolved photoemission spectroscopy Open
The recently discovered layered kagome superconductors A V 3 Sb 5 ( A = K, Rb, Cs) have garnered significant attention, as they exhibit an intriguing combination of superconductivity, charge density wave (CDW) order, and nontrivial band to…
View article: Fate of Bosonic Topological Edge Modes in the Presence of Many-Body Interactions
Fate of Bosonic Topological Edge Modes in the Presence of Many-Body Interactions Open
Many magnetic materials are predicted to exhibit bosonic topological edge modes in their excitation spectra, because of the nontrivial topology of their magnon, triplon, or other quasi-particle band structures. However, there is a discrepa…
View article: Phonon promoted charge density wave in topological kagome metal ScV6Sn6
Phonon promoted charge density wave in topological kagome metal ScV6Sn6 Open
Charge density wave (CDW) orders in vanadium-based kagome metals have recently received tremendous attention due to their unique properties and intricate interplay with exotic correlated phenomena, topological and symmetry-breaking states.…
View article: Electronic Landscape of Kagome Superconductors $\textit{A}$V$_{3}$Sb$_{5}$ ($\textit{A}$ = K, Rb, Cs) from Angle-Resolved Photoemission Spectroscopy
Electronic Landscape of Kagome Superconductors $\textit{A}$V$_{3}$Sb$_{5}$ ($\textit{A}$ = K, Rb, Cs) from Angle-Resolved Photoemission Spectroscopy Open
The recently discovered layered kagome superconductors $\textit{A}$V$_{3}$Sb$_{5}$ ($\textit{A}$ = K, Rb, Cs) have garnered significant attention, as they exhibit an intriguing combination of superconductivity, charge density wave (CDW) or…
View article: Multi-locational Majorana Zero Modes
Multi-locational Majorana Zero Modes Open
We show the appearance of an unconventional Majorana zero mode whose wave function splits into multiple parts located at different ends of different topological superconductors, hereinafter referred to as a multi-locational Majorana zero m…
View article: Correlation Induced Magnetic Topological Phases in Mixed-Valence Compound SmB6
Correlation Induced Magnetic Topological Phases in Mixed-Valence Compound SmB6 Open
SmB6 is a mixed-valence compound with flat f-electron bands that have a propensity to magnetism. Here, using a realistic Gamma8 quartet model, we investigate the dynamical spin susceptibility and describe the in-gap collective mode observe…