Heisenberg model
View article
<i>Colloquium</i>: Herbertsmithite and the search for the quantum spin liquid Open
Quantum spin liquids form a novel class of matter where, despite the existence of strong exchange interactions, spins do not order down to the lowest measured temperature. Typically, these occur in lattices that act to frustrate the appear…
View article
Kardar-Parisi-Zhang Physics in the Quantum Heisenberg Magnet Open
Equilibrium spatiotemporal correlation functions are central to understanding weak nonequilibrium physics. In certain local one-dimensional classical systems with three conservation laws they show universal features. Namely, fluctuations a…
View article
Approximating quantum many-body wave functions using artificial neural networks Open
In this paper, we demonstrate the expressibility of artificial neural\nnetworks (ANNs) in quantum many-body physics by showing that a feed-forward\nneural network with a small number of hidden layers can be trained to\napproximate with hig…
View article
Milestones of low-D quantum magnetism Open
There is a long time gap between the formulation of the basic theory of low-dimensional (low-D) magnetism as advanced by Ising, Heisenberg and Bethe and its experimental verification. The latter started not long before the discovery of hig…
View article
Superdiffusion in One-Dimensional Quantum Lattice Models Open
We identify a class of one-dimensional spin and fermionic lattice models that display diverging spin and charge diffusion constants, including several paradigmatic models of exactly solvable, strongly correlated many-body dynamics such as …
View article
Quantum correlations and coherence in spin-1 Heisenberg chains Open
We explore quantum and classical correlations along with coherence in the ground states of spin-1 Heisenberg chains, namely the one-dimensional XXZ model and the one-dimensional bilinear biquadratic model, with the techniques of density ma…
View article
Dynamics of the Kitaev-Heisenberg Model Open
We introduce a matrix-product state based method to efficiently obtain dynamical response functions for two-dimensional microscopic Hamiltonians. We apply this method to different phases of the Kitaev-Heisenberg model and identify characte…
View article
Honeycomb-Lattice Heisenberg-Kitaev Model in a Magnetic Field: Spin Canting, Metamagnetism, and Vortex Crystals Open
The Heisenberg-Kitaev model is a paradigmatic model to describe the magnetism in honeycomb-lattice Mott insulators with strong spin-orbit coupling, such as A_{2}IrO_{3} (A=Na, Li) and α-RuCl_{3}. Here, we study in detail the physics of the…
View article
Bootstrapping Heisenberg magnets and their cubic instability Open
We study the critical O(3) model using the numerical conformal bootstrap. In particular, we use a recently developed cutting-surface algorithm to efficiently map out the allowed space of conformal field theory data from correlators involvi…
View article
Ballistic Spin Transport in a Periodically Driven Integrable Quantum System Open
We demonstrate ballistic spin transport of an integrable unitary quantum circuit, which can be understood either as a paradigm of an integrable periodically driven (Floquet) spin chain, or as a Trotterized anisotropic (XXZ) Heisenberg spin…
View article
Spin-orbit excitation energies, anisotropic exchange, and magnetic phases of honeycomb RuCl3 Open
Using quantum chemistry calculations we shed fresh light on the electronic structure and magnetic properties of RuCl3, a proposed realization of the honeycomb Kitaev spin model. It is found that the nearest-neighbor Kitaev exchange K is we…
View article
Topological excitations in the ferromagnetic Kitaev-Heisenberg model Open
With the advancement in synthesizing and analyzing Kitaev materials, the\nKitaev-Heisenberg model on the honeycomb lattice has attracted a lot of\nattention in the last few years. Several variations, which include additional\nanisotropic i…
View article
Microscopic Origin of Heisenberg and Non-Heisenberg Exchange Interactions in Ferromagnetic bcc Fe Open
By means of first principles calculations, we investigate the nature of exchange coupling in ferromagnetic bcc Fe on a microscopic level. Analyzing the basic electronic structure reveals a drastic difference between the 3d orbitals of E_{g…
View article
Exact steady states for quantum quenches in integrable Heisenberg spin chains Open
The study of quantum quenches in integrable systems has significantly\nadvanced with the introduction of the Quench Action method, a versatile\nanalytical approach to non-equilibrium dynamics. However, its application is\nlimited to those …
View article
Systematic derivation of realistic spin models for beyond-Heisenberg solids Open
We present a systematic derivation of effective lattice spin Hamiltonians\nderived from a rotationally invariant multi-orbital Hubbard model including a\nterm ensuring Hund's rule coupling. The Hamiltonians are derived down-folding\nthe fe…
View article
Quantum Spin Liquids in Frustrated Spin-1 Diamond Antiferromagnets Open
Motivated by the recent synthesis of the spin-1 A-site spinel NiRh2O4, we investigate the classical to quantum crossover of a frustrated J1−J2 Heisenberg model on the diamond lattice upon varying the spin length S. Applying a recently deve…
View article
Witnessing entanglement in quantum magnets using neutron scattering Open
We demonstrate how quantum entanglement can be directly witnessed in the\nquasi-1D Heisenberg antiferromagnet KCuF$_3$. We apply three entanglement\nwitnesses --- one-tangle, two-tangle, and quantum Fisher information --- to its\ninelastic…
View article
Spectral signatures of fractionalization in the frustrated Heisenberg model on the square lattice Open
We employ a variational Monte Carlo approach to efficiently obtain the dynamical structure factor for the spin-1/2 $J_1-J_2$ Heisenberg model on the square lattice. Upon increasing the frustrating ratio $J_2/J_1$, the ground state undergoe…
View article
Yang–Baxter integrable models in experiments: from condensed matter to ultracold atoms Open
The Yang-Baxter equation has long been recognised as the masterkey to\nintegrability, providing the basis for exactly solved models which capture the\nfundamental physics of a number of realistic classical and quantum systems. In\nthis art…
View article
Spin transport of weakly disordered Heisenberg chain at infinite temperature Open
We study the disordered Heisenberg spin chain, which exhibits many body\nlocalization at strong disorder, in the weak to moderate disorder regime. A\ncontinued fraction calculation of dynamical correlations is devised, using a\nvariational…
View article
Quantum and Classical Phases of the Pyrochlore Heisenberg Model with Competing Interactions Open
We investigate the quantum Heisenberg model on the pyrochlore lattice for a generic spin $S$ in the presence of nearest-neighbor $J_{1}$ and second-nearest-neighbor $J_{2}$ exchange interactions. By employing the pseudofermion functional r…
View article
Critical behavior of dissipative two-dimensional spin lattices Open
We explore critical properties of two-dimensional lattices of spins interacting via an anisotropic Heisenberg Hamiltonian that are subject to incoherent spin flips. We determine the steady-state solution of the master equation for the dens…
View article
Quantum critical phase with infinite projected entangled paired states Open
International audience
View article
Simulating excitation spectra with projected entangled-pair states Open
We develop and benchmark a technique for simulating excitation spectra of\ngeneric two-dimensional quantum lattice systems using the framework of\nprojected entangled-pair states (PEPS). The technique relies on a variational\nansatz for ca…
View article
Designing Magnetism in High Entropy Oxides Open
In magnetic systems, spin and exchange disorder can provide access to quantum criticality, frustration, and spin dynamics, but broad tunability of these responses and a deeper understanding of strong limit disorder are lacking. Here, it is…
View article
Optimal phase space sampling for Monte Carlo simulations of Heisenberg spin systems Open
We present an adaptive algorithm for the optimal phase space sampling in Monte Carlo simulations of 3D Heisenberg spin systems. Based on a golden rule of the Metropolis algorithm which states that an acceptance rate of [Formula: see text] …
View article
Phase diagram and spin correlations of the Kitaev-Heisenberg model: Importance of quantum effects Open
We explore the phase diagram of the Kitaev-Heisenberg model with nearest\nneighbor interactions on the honeycomb lattice using the exact diagonalization\nof finite systems combined with the cluster mean field approximation, and\nsupplement…
View article
Dynamical structure factor of the triangular antiferromagnet: Schwinger boson theory beyond mean field Open
We compute the zero-temperature dynamical structure factor S(q,ω) of the triangular lattice Heisenberg model (TLHM) using a Schwinger boson approach that includes the Gaussian fluctuations (1/N corrections) of the saddle-point solution. Wh…
View article
Spin Waves and Magnetic Exchange Hamiltonian in CrSBr Open
CrSBr is an air‐stable two‐dimensional (2D) van der Waals semiconducting magnet with great technological promise, but its atomic‐scale magnetic interactions—crucial information for high‐frequency switching—are poorly understood. An experim…
View article
Kitaev materials beyond iridates: Order by quantum disorder and Weyl magnons in rare-earth double perovskites Open
Motivated by the experiments on the rare-earth double perovskites, we propose a generalized Kitaev-Heisenberg model to describe the generic interaction between the spin-orbit-entangled Kramers' doublets of the rare-earth moments. We carry …