A5017799932- Advanced Condensed Matter Physics
- Physics of Superconductivity and Magnetism
- Quantum many-body systems
- Theoretical and Computational Physics
- Quantum, superfluid, helium dynamics
- Topological Materials and Phenomena
- Magnetic and transport properties of perovskites and related materials
- Cold Atom Physics and Bose-Einstein Condensates
- Perovskite Materials and Applications
- Nuclear materials and radiation effects
- Quantum Chromodynamics and Particle Interactions
Helmholtz-Zentrum Berlin für Materialien und Energie
2021-2024
Freie Universität Berlin
2019-2024
We investigate the ground-state properties of spin-$1/2$ pyrochlore Heisenberg antiferromagnet using pseudofermion functional renormalization group techniques. The first part our analysis is based on an enhanced parton mean-field approach, which takes into account fluctuation effects from renormalized vertex functions. Our implementation this technique extends earlier approaches and resolves technical difficulties associated with a diagrammatic overcounting. Using various ans\"atze for...
Gauge theories are powerful theoretical physics tools that allow complex phenomena to be reduced simple principles and used in both high-energy condensed matter physics. In the latter context, gauge becoming increasingly popular for capturing intricate spin correlations liquids, exotic states of which dynamics quantum spins never ceases, even at absolute zero temperature. We consider a system on three-dimensional pyrochlore lattice where emergent fields not only describe liquid behavior...
Quantum spin liquids (QSLs) have become a key area of research in magnetism due to their remarkable properties, such as long-range entanglement, fractional excitations, and topologically protected phenomena. Recently, the search for QSLs has expanded into three-dimensional world, despite suppression quantum fluctuations high dimensionality. A new candidate material, K2Ni2(SO4)3, belongs langbeinite family consists two interconnected trillium lattices. Although magnetically ordered, it...
Quantum spin liquids are exotic states of matter that form when strongly frustrated magnetic interactions induce a highly entangled quantum paramagnet far below the energy scale interactions. Three-dimensional cases especially challenging due to significant reduction influence fluctuations. Here, we report characterization K_{2}Ni_{2}(SO_{4})_{3} forming three-dimensional network Ni^{2+} spins. Using density functional theory calculations, show this consists two interconnected spin-1...
We investigate the ground state and critical temperature (${T}_{c}$) phase diagrams of classical quantum $S=\frac{1}{2}$ pyrochlore lattice with nearest-neighbor Heisenberg Dzyaloshinskii-Moriya interactions (DMI). consider ferromagnetic antiferromagnetic exchange interaction as well direct indirect DMI. At level, three states are found: all-in/all-out, ferromagnetic, a locally ordered $XY$ phase, known ${\mathrm{\ensuremath{\Gamma}}}_{5}$, which displays an accidental U(1) degeneracy at...
In the field of quantum magnetism, advent numerous spin-orbit assisted Mott insulating compounds, such as family Kitaev materials, has led to a growing interest in studying general spin models with nondiagonal interactions that do not retain SU(2) invariance underlying degrees freedom. However, exchange frustration arising from these and often bond-directional for two- three-dimensional lattice geometries poses serious challenge numerical many-body simulation techniques. this paper, we...
The pseudo-fermion functional renormalization group is generalized to treat spin Hamiltonians with finite magnetic fields, enabling its application arbitrary lattice models linear and bilinear terms in the operators. We discuss detail an efficient numerical implementation of this approach making use system's symmetries. Particularly, we demonstrate that inclusion small symmetry-breaking seed fields regularizes divergences susceptibility at phase transitions. This allows investigation within...
We investigate the ground-state properties of nearest-neighbor $S=1$ pyrochlore Heisenberg antiferromagnet using two complementary numerical methods, density-matrix renormalization group (DMRG) and pseudofermion functional (PFFRG). Within DMRG, we are able to reliably study clusters with up 48 spins by keeping 20 000 SU(2) states. The investigated 32-site 48-site both show indications a robust ${C}_{3}$ rotation symmetry breaking spin correlations cluster additionally features inversion...
Quantum spin liquids (QSLs) have become a key area of research in magnetism due to their remarkable properties, such as long-range entanglement, fractional excitations, pinch-point singularities, and topologically protected phenomena. In recent years, the search for QSLs has expanded into three-dimensional world, where promising features been found materials that form pyrochlore hyper-kagome lattices, despite suppression quantum fluctuations high dimensionality. One material is $S = 1$...
Gauge theories are powerful tools in theoretical physics, allowing complex phenomena to be reduced simple principles, and used both high-energy condensed matter physics. In the latter context, gauge becoming increasingly popular for capturing intricate spin correlations liquids, exotic states of which dynamics quantum spins never ceases, even at absolute zero temperature. We consider a system on three-dimensional pyrochlore lattice where emergent fields not only describe liquid behaviour...
The pseudo-fermion functional renormalization group is generalized to treat spin Hamiltonians with finite magnetic fields, enabling its application arbitrary lattice models linear and bilinear terms in the operators. We discuss detail an efficient numerical implementation of this approach making use system's symmetries. Particularly, we demonstrate that inclusion small symmetry breaking seed fields regularizes divergences susceptibility at phase transitions. This allows investigation within...
We investigate the ground state and critical temperature phase diagrams of classical quantum $S=1/2$ pyrochlore lattice with nearest-neighbor Heisenberg Dzyaloshinskii-Moriya interactions (DMI). consider ferromagnetic antiferromagnetic exchange as well direct indirect DMI. Classically, three states are found: all-in/all-out, a locally ordered $XY$ phase, known $Γ_5$, which displays an accidental U(1) degeneracy. Quantum zero-point energy fluctuations found to lift degeneracy select $ψ_3$ in...
We investigate the ground-state properties of nearest-neighbor $S=1$ pyrochlore Heisenberg antiferromagnet using two complementary numerical methods, density-matrix renormalization group (DMRG) and pseudofermion functional (PFFRG). Within DMRG, we are able to reliably study clusters with up 48 spins by keeping 20 000 SU(2) states. The investigated 32-site 48-site both show indications a robust $C_3$ rotation symmetry breaking spin correlations cluster additionally features inversion...