Publications (66)
Exchangeless braiding of Majorana zero modes in weakly coupled Kitaev chains
Robin Quade, Michael Potthoff
Exchangeless braiding of Majorana modes is studied in minimal networks of weakly hybridized Kitaev chains of finite length using a rigorous many-body framework. In particular, for…
Non-collinear spin states in bottom-up fabricated atomic chains
Manuel Steinbrecher, Roman Rausch, Khai Ton That +5
Non-collinear spin states with unique rotational sense, such as chiral spin-spirals, are recently heavily investigated because of advantages for future applications in spintronics…
Phase diagram of the Kondo model on the zigzag ladder
Matthias Peschke, Lena-Marie Woelk, Michael Potthoff
The effect of next-nearest-neighbor hopping on the ground-state phase diagram of the one-dimensional Kondo lattice is studied with density-matrix renormalization-group tech…
Screening mechanisms in magnetic nanostructures
Andrej Schwabe, Mirek Hänsel, Michael Potthoff +1
A theoretical concept is presented for the screening of several magnetic moments locally exchange coupled to conduction electrons in a metallic nanostructure. We consider a quantum…
Inverse indirect magnetic exchange
Andrej Schwabe, Irakli Titvinidze, Michael Potthoff
Magnetic moments strongly coupled to the spins of conduction electrons in a nanostructure can confine the conduction-electron motion due to scattering at almost localized Kondo sin…
Krylov-space approach to the equilibrium and the nonequilibrium single-particle Green's function
Matthias Balzer, Nadine Gdaniec, Michael Potthoff
The zero-temperature single-particle Green's function of correlated fermion models with moderately large Hilbert-space dimensions can be calculated by means of Krylov-space techniq…
Prerelaxation in quantum, classical, and quantum-classical two-impurity models
Michael Elbracht, Michael Potthoff
We numerically study the relaxation dynamics of impurity-host systems, focusing on the presence of long-lived metastable states in the non-equilibrium dynamics after an initial exc…
Magnetic Doublon Bound States in the Kondo Lattice Model
Roman Rausch, Michael Potthoff, Norio Kawakami
We present a novel pairing mechanism for electrons, mediated by magnons. These paired bound states are termed ``magnetic doublons''. Applying numerically exact techniques (full dia…
Geometrical torque on magnetic moments coupled to a correlated antiferromagnet
Nicolas Lenzing, David Krüger, Michael Potthoff
The geometrical spin torque mediates an indirect interaction of magnetic moments, which are weakly exchange coupled to a system of itinerant electrons. It originates from a finite…
Self-energy-functional theory for systems of interacting electrons with disorder
Michael Potthoff, Matthias Balzer
Based on a functional-integral formalism, a generalization of the self-energy-functional theory (SFT) is proposed which is applicable to systems of interacting electrons with disor…
Doublon dynamics in the extended Fermi Hubbard model
Felix Hofmann, Michael Potthoff
Two fermions occupying the same site of a lattice model with strongly repulsive Hubbard-type interaction U form a doublon, a long-living excitation the decay of which is suppressed…
Competition between Kondo screening and indirect magnetic exchange in a quantum box
Andrej Schwabe, Daniel Gütersloh, Michael Potthoff
Nanoscale systems of metal atoms antiferromagnetically exchange coupled to several magnetic impurities are shown to exhibit an unconventional re-entrant competition between Kondo s…
Anomalous spin precession under a geometrical torque
Christopher Stahl, Michael Potthoff
Precession and relaxation predominantly characterize the real-time dynamics of a spin driven by a magnetic field and coupled to a large Fermi sea of conduction electrons. We demons…
Dynamical mean-field study of partial Kondo screening in the periodic Anderson model on the triangular lattice
Maximilian W. Aulbach, Fakher F. Assaad, Michael Potthoff
The competition between Kondo screening and indirect magnetic exchange is studied for a system with geometrical frustration using dynamical mean-field theory (DMFT). We systematica…
Macrospin approximation and quantum effects in models for magnetization reversal
Mohammad Sayad, Daniel Gütersloh, Michael Potthoff
The thermal activation of magnetization reversal in magnetic nanoparticles is controlled by the anisotropy-energy barrier. Using perturbation theory, exact diagonalization and stab…
Non-Hamiltonian dynamics of indirectly coupled classical impurity spins
Simon Michel, Michael Potthoff
We discuss the emergence of an effective low-energy theory for the real-time dynamics of two classical impurity spins within the framework of a prototypical and purely classical mo…
Non-equilibrium cluster-perturbation theory
Matthias Balzer, Michael Potthoff
The cluster perturbation theory (CPT) is one of the simplest but systematic quantum cluster approaches to lattice models of strongly correlated electrons with local interactions. B…
Crossover from conventional to inverse indirect magnetic exchange in the depleted Anderson lattice
Maximilian W. Aulbach, Irakli Titvinidze, Michael Potthoff
We investigate the finite-temperature properties of an Anderson lattice with regularly depleted impurities. The physics of this model is ruled by two different magnetic exchange me…
Non-perturbative conserving approximations and Luttinger's sum rule
Jutta Ortloff, Matthias Balzer, Michael Potthoff
Weak-coupling conserving approximations can be constructed by truncations of the Luttinger-Ward functional and are well known as thermodynamically consistent approaches which respe…
Systematics of approximations constructed from dynamical variational principles
Michael Potthoff
The systematics of different approximations within the self-energy-functional theory (SFT) is discussed for fermionic lattice models with local interactions. In the context of the…
Self-energy-functional approach to systems of correlated electrons
Michael Potthoff
The grand potential of a system of interacting electrons is considered as a stationary point of a self-energy functional. It is shown that a rigorous evaluation of the functional i…
Dynamical variational principles for strongly correlated electron systems
Michael Potthoff
The self-energy-functional approach (SFA) is discussed in the context of different variational principles for strongly correlated electron systems. Formal analogies between static…
Spin Berry curvature of the Haldane model
Simon Michel, Michael Potthoff
The feedback of the geometrical Berry phase, accumulated in an electron system, on the slow dynamics of classical degrees of freedom is governed by the Berry curvature. Here, we st…
Nonequilibrium variational-cluster approach to real-time dynamics in the Fermi-Hubbard model
Felix Hofmann, Martin Eckstein, Michael Potthoff
The nonequilibrium variational-cluster approach is applied to study the real-time dynamics of the double occupancy in the one-dimensional Fermi-Hubbard model after different fast c…
Bound states and local topological phase diagram of classical impurity spins coupled to a Chern insulator
Simon Michel, Axel Fünfhaus, Robin Quade +2
The existence of bound states induced by local impurities coupled to an insulating host depends decisively on the global topological properties of the host's electronic structure.…
Mott transition in one dimension: Benchmarking dynamical cluster approaches
Matthias Balzer, Werner Hanke, Michael Potthoff
The variational cluster approach (VCA) is applied to the one-dimensional Hubbard model at zero temperature using clusters (chains) of up to ten sites with full diagonalization and…
Making use of self-energy functionals: The variational cluster approximation
Michael Potthoff
A pedagogical introduction to the cluster-perturbation theory, the variational cluster approximation and to self-energy-functional theory is given. Some standard applications and t…
Boundary and finite-size effects in the competition between indirect magnetic exchange and Kondo screening
Irakli Titvinidze, Michael Potthoff
A system of conduction electrons can mediate an indirect magnetic exchange between magnetic impurites. The nonlocal exchange typically competes with the local Kondo screening of th…
Time-dependent Mott transition in the periodic Anderson model with nonlocal hybridization
Felix Hofmann, Michael Potthoff
The time-dependent Mott transition in a periodic Anderson model with off-site, nearest-neighbor hybridization is studied within the framework of nonequilibrium self-energy function…
Lehmann representation of the nonequilibrium self-energy
Christian Gramsch, Michael Potthoff
It is shown that the non-equilibrium self-energy of an interacting lattice-fermion model has a unique Lehmann representation. Based on the construction of a suitable non-interactin…
Topological spin torque emerging in classical-spin systems with different time scales
Michael Elbracht, Simon Michel, Michael Potthoff
In classical spin systems with two largely different inherent time scales, the configuration of the fast spins almost instantaneously follows the slow-spin dynamics. We develop the…
Disorder- and correlation-driven metal-insulator transitions
Matthias Balzer, Michael Potthoff
Metal-insulator transitions driven by disorder (Delta) and/or by electron correlations (U) are investigated within the Anderson-Hubbard model with local binary-alloy disorder using…
Long-time relaxation dynamics of a spin coupled to a Chern insulator
Michael Elbracht, Michael Potthoff
The relaxation of a classical spin, exchange coupled to the local magnetic moment at an edge site of the one-dimensional spinful Su-Schrieffer-Heeger model is studied numerically b…
Dynamical mean-field theory of indirect magnetic exchange
Irakli Titvinidze, Andrej Schwabe, Niklas Rother +1
To analyze the physical properties arising from indirect magnetic exchange between several magnetic adatoms and between complex magnetic nanostructures on metallic surfaces, the re…
Microscopic theory of spin friction and dissipative spin dynamics
Nicolas Lenzing, David Krüger, Michael Potthoff
The real-time dynamics of local magnetic moments exchange coupled to a metallic system of conduction electrons is subject to dissipative friction even in the absence of spin-orbit…
Density-matrix functionals from Greens functions
Peter E. Blöchl, Thomas Pruschke, Michael Potthoff
The exact reduced density-matrix functional is derived from the Luttinger-Ward functional of the single-particle Green's function. Thereby, a formal link is provided between diagra…
Dynamical symmetry between spin and charge excitations studied by a plaquette mean-field approach in two dimensions
Philipp Jurgenowski, Michael Potthoff
The real-time dynamics of local occupation numbers in a Hubbard model on a 6x6 square lattice is studied by means of the non-equilibrium generalization of the cluster-perturbation…
Spin dynamics and relaxation in the classical-spin Kondo-impurity model beyond the Landau-Lifschitz-Gilbert equation
Mohammad Sayad, Michael Potthoff
The real-time dynamics of a classical spin in an external magnetic field and locally exchange coupled to an extended one-dimensional system of non-interacting conduction electrons…
First order Mott transition at zero temperature in two dimensions: Variational plaquette study
Matthias Balzer, Bumsoo Kyung, David Sénéchal +2
The nature of the metal-insulator Mott transition at zero temperature has been discussed for a number of years. Whether it occurs through a quantum critical point or through a firs…
Anomalous magnetic anisotropy of the topmost surface layer of Ni(110)
Marco Busch, Jens Lienemann, Michael Potthoff +1
The orientation of the magnetization of a Ni(110) surface was investigated using techniques with different probing depths. By making use of electron capture into excited states of…
Nonequilibrium self-energy functional approach to the dynamical Mott transition
Felix Hofmann, Martin Eckstein, Michael Potthoff
The real-time dynamics of the Fermi-Hubbard model, driven out of equilibrium by quenching or ramping the interaction parameter, is studied within the framework of the nonequilibriu…
Static and dynamic variational principles for strongly correlated electron systems
Michael Potthoff
The equilibrium state of a system consisting of a large number of strongly interacting electrons can be characterized by its density operator. This gives a direct access to the gro…
Non-perturbative construction of the Luttinger-Ward functional
Michael Potthoff
For a system of correlated electrons, the Luttinger-Ward functional provides a link between static thermodynamic quantities on the one hand and single-particle excitations on the o…
Inertia effects in the real-time dynamics of a quantum spin coupled to a Fermi sea
Mohammad Sayad, Roman Rausch, Michael Potthoff
Spin dynamics in the Kondo impurity model, initiated by suddenly switching the direction of a local magnetic field, is studied by means of the time-dependent density-matrix renorma…
Relaxation of a classical spin coupled to a strongly correlated electron system
Mohammad Sayad, Roman Rausch, Michael Potthoff
A classical spin which is antiferromagnetically coupled to a system of strongly correlated conduction electrons is shown to exhibit unconventional real-time dynamics which cannot b…
Kondo Screening and Indirect Magnetic Exchange through a Conventional Superconductor Studied by the Density-Matrix Renormalization Group
Cassian Plorin, Michael Potthoff
The competition between the Kondo screening and indirect magnetic exchange in systems with two magnetic impurities coupled to a conventional s-wave superconductor gives rise to a n…
Self-energy-functional theory
Michael Potthoff
Self-energy-functional theory is a formal framework which allows to derive non-perturbative and thermodynamically consistent approximations for lattice models of strongly correlate…
Nonequilibrium self-energy functional theory
Felix Hofmann, Martin Eckstein, Enrico Arrigoni +1
The self-energy functional theory (SFT) is generalized to describe the real-time dynamics of correlated lattice-fermion models far from thermal equilibrium. This is achieved by mea…
Frustrated quantum magnetism in the Kondo lattice on the zigzag ladder
Matthias Peschke, Roman Rausch, Michael Potthoff
The interplay between Kondo effect, indirect magnetic interaction and geometrical frustration is studied in the Kondo lattice on the one-dimensional zigzag ladder. Using the densit…
Band model for the understanding of ferromagnetism in semiconductors and insulators
Mirek Hänsel, Wolfgang Nolting, Michael Potthoff
To investigate ferromagnetic semiconductors and insulators, such as the famous EuO, EuS, or CrBr, we propose a hybridized Kondo-lattice model, where, in addition to the conduct…
Importance of local correlations for the order parameter of high-Tc superconductors
Matthias Balzer, Werner Hanke, Michael Potthoff
It is shown that local temporal correlations in addition to non-local spatial correlations are important to understand the size and the doping dependence of the d-wave superconduct…
Ferromagnetism of magnetic impurities coupled indirectly via conduction electrons: Insights from various theoretical approaches
Irakli Titvinidze, Andrej Schwabe, Michael Potthoff
The magnetic ground-state properties of the periodic Anderson model with a regular depletion of the correlated sites are analyzed within different theoretical approaches. We consid…
Pump-probe Auger-electron spectroscopy of Mott insulators
Roman Rausch, Michael Potthoff
In high-resolution core-valence-valence (CVV) Auger electron spectroscopy from the surface of a solid at thermal equilibrium, the main correlation satellite, visible in the case of…
Multiplons in the two-hole excitation spectra of the one-dimensional Hubbard model
Roman Rausch, Michael Potthoff
Using the density-matrix renormalization group in combination with the Chebyshev polynomial expansion technique, we study the two-hole excitation spectrum of the one-dimensional Hu…
Controlling the real-time dynamics of a spin coupled to the helical edge states of the Kane-Mele model
Robin Quade, Michael Potthoff
The time-dependent state of a classical spin locally exchange coupled to an edge site of a Kane-Mele model in the topologically non-trivial phase is studied numerically by solving…
Cooperation of different exchange mechanisms in confined magnetic systems
Andrej Schwabe, Mirek Hänsel, Michael Potthoff
The diluted Kondo lattice model is investigated at strong antiferromagnetic local exchange couplings J, where almost local Kondo clouds drastically restrict the motion of conductio…
Filling-dependent doublon dynamics in the one-dimensional Hubbard model
Roman Rausch, Michael Potthoff
The fate of a local two-hole doublon excitation in the one-dimensional Fermi-Hubbard model is systematically studied for strong Hubbard interaction U in the entire filling range us…
Disorder-Induced Topological Phases in a Two-Dimensional Chern Insulator with Strong Magnetic Disorder
Devesh Vaish, Michael Potthoff
Strong directional disorder in local magnetic moments coupled to a Chern insulator gives rise to topological phases that cannot be continuously connected to the clean limit and are…
Enforcing conservation laws in nonequilibrium cluster perturbation theory
Christian Gramsch, Michael Potthoff
Using the recently introduced time-local formulation of the nonequilibrium cluster perturbation theory (CPT), we construct a generalization of the approach such that macroscopic co…
Accessing long timescales in the relaxation dynamics of spins coupled to a conduction-electron system using absorbing boundary conditions
Michael Elbracht, Michael Potthoff
The relaxation time of a classical spin interacting with a large conduction-electron system is computed for a weak magnetic field, which initially drives the spin out of equilibriu…
Variational cluster approach to ferromagnetism in infinite dimensions and in one-dimensional chains
Matthias Balzer, Michael Potthoff
The variational cluster approach (VCA) is applied to study spontaneous ferromagnetism in the Hubbard model at zero temperature. We discuss several technical improvements of the num…
Emergent Non-Abelian Gauge Theory in Coupled Spin-Electron Dynamics
Nicolas Lenzing, Alexander I. Lichtenstein, Michael Potthoff
A clear separation of the time scales governing the dynamics of "slow" and "fast" degrees of freedom often serves as a prerequisite for the emergence of an independent low-energy t…
Interacting Chern Insulator in Infinite Spatial Dimensions
David Krüger, Michael Potthoff
We study a generic model of a Chern insulator supplemented by a Hubbard interaction in arbitrary even dimension and demonstrate that the model remains well-defined and nontrivi…
Strong-coupling limit of depleted Kondo- and Anderson-lattice models
Irakli Titvinidze, Andrej Schwabe, Michael Potthoff
Fourth-order strong-coupling degenerate perturbation theory is used to derive an effective low-energy Hamiltonian for the Kondo-lattice model with a depleted system of localized sp…
Accessing thermodynamics from dynamical cluster-embedding approaches
Gang Li, Werner Hanke, Alexei N. Rubtsov +2
Dynamical quantum-cluster approaches, such as different cluster extensions of the dynamical mean-field theory (cluster DMFT) or the variational cluster approximation (VCA), combine…
Correlated band structure and the ground-state phase diagram in high-Tc cuprates
Werner Hanke, Markus Aichhorn, Enrico Arrigoni +1
We review results obtained with a recently proposed variational cluster approach (VCA) for the competition between d-wave superconductivity (dSC) and antiferromagnetism (AF) in the…