@article{SchmeisserSeiboldReif, author = {Schmeißer, Dieter and Seibold, G{\"o}tz and Reif, J{\"u}rgen}, title = {Nano-scaled Dielectric Barriers (NanoDieB) for CMOS compatible Si-technologies}, series = {Forum der Forschung}, journal = {Forum der Forschung}, number = {19}, issn = {0947-6989}, pages = {131 -- 136}, language = {en} } @misc{Seibold, author = {Seibold, G{\"o}tz}, title = {On the Evaluation of Higher-Harmonic-Current Responses for High-Field Spectroscopies in Disordered Superconductors}, series = {Condensed Matter}, volume = {8}, journal = {Condensed Matter}, number = {4}, issn = {2410-3896}, doi = {10.3390/condmat8040095}, pages = {1 -- 16}, abstract = {We discuss a formalism that allows for the calculation of a higher-harmonic-current response to a strong applied electric field for disordered superconducting systems described on the basis of tight-binding models with on- and/or intersite interactions. The theory is based on an expansion of the density matrix in powers of the field amplitudes, where we solve the equation of motion for the individual components. This allows the evaluation of higher-order response functions on significantly larger lattices than one can achieve with a previously used approach, which is based on a direct temporal integration of the equation of motion for the complete density matrix. In the case of small lattices, where both methods can be applied by including also the contribution of collective modes, we demonstrate the agreement of the corresponding results.}, language = {en} } @misc{SeiboldPickhardt, author = {Seibold, G{\"o}tz and Pickhardt, Michael}, title = {Lapse of time effects on tax evasion in an agent-based econophysics model}, series = {Physica A: Statistical Mechanics and its Applications}, volume = {392}, journal = {Physica A: Statistical Mechanics and its Applications}, number = {9}, issn = {0378-4371}, doi = {10.1016/j.physa.2013.01.016}, pages = {2079 -- 2087}, abstract = {We investigate an inhomogeneous Ising model in the context of tax evasion dynamics where different types of agents are parameterized via local temperatures and magnetic fields. In particular, we analyze the impact of lapse of time effects (i.e. backauditing) and endogenously determined penalty rates on tax compliance. Both features contribute to a microfoundation of agent-based econophysics models of tax evasion.}, language = {en} } @article{SigmundSeiboldBilletal., author = {Sigmund, Ernst and Seibold, G{\"o}tz and Bill, Andreas and Wulf, Ulrich and Isenmann, G. and Essl, W.}, title = {Dynamische Eigenschaften von Festk{\"o}rpern und Molekularen Strukturen}, language = {en} } @article{SeiboldSigmund, author = {Seibold, G{\"o}tz and Sigmund, Ernst}, title = {Gutzwiller and Slave-Boson Methods for Intersite Coulomb Interactions}, language = {en} } @phdthesis{Seibold, author = {Seibold, G{\"o}tz}, title = {Spin-polarisierte Quasiteilchen in der Hochtemperatursupraleitung}, publisher = {Aachen : Shaker}, language = {de} } @misc{SeiboldUdinaCastellanietal., author = {Seibold, G{\"o}tz and Udina, Mattia and Castellani, Claudio and Benfatto, Lara}, title = {Third harmonic generation from collective modes in disordered superconductors}, series = {Physical Review B}, volume = {103}, journal = {Physical Review B}, number = {1}, doi = {10.1103/PhysRevB.103.014512}, pages = {19}, abstract = {Recent experiments with strong THz fields in both conventional and unconventional superconductors have clearly evidenced a marked third-harmonic generation below the superconducting temperature Tc. Its interpretation challenged substantial theoretical work aimed at establishing the relative efficiency of quasiparticle excitations and collective modes in triggering such a resonant response. Here we compute the nonlinear current by implementing a time-dependent Bogoljubov-de Gennes approach, with the twofold aim to account nonperturbatively for the effect of local disorder, and to include the contribution of all collective modes, i.e., superconducting amplitude (Higgs) and phase fluctuations, and charge fluctuations. We show that, in agreement with previous work, already at small disorder the quasiparticle response is dominated by paramagnetic effects. We further demonstrate that paramagnetic processes mediate also the response of all collective modes, with a substantial contribution of charge/phase fluctuations. These processes, which have been overlooked so far, turn out to dominate the third-order current at strong disorder. In addition, we show that disorder strongly influences the polarization dependence of the nonlinear response, with a marked difference between the clean and the disordered case. Our results are particularly relevant for recent experiments in cuprates, whose band structure is in a first approximation reproduced by our lattice model.}, language = {en} } @misc{SeiboldCastellaniLorenzana, author = {Seibold, G{\"o}tz and Castellani, Claudio and Lorenzana, Jos{\´e}}, title = {Adiabatic transition from a BCS superconductor to a Fermi liquid and phase dynamics}, series = {Physical Review B}, volume = {105}, journal = {Physical Review B}, number = {18}, issn = {2469-9969}, doi = {10.1103/PhysRevB.105.184513}, pages = {184513-1 -- 184513-14}, abstract = {We investigate the physics of an adiabatic transition from a BCS superconductor to a Fermi liquid for an exponentially slow decreasing pairing interaction. We show that, depending on the order of the thermodynamic limit and large times, a situation can arise in which the Fermi liquid keeps a memory of the parent BCS state. Furthermore, a time inversion of the interaction, supplemented by a manipulation analogous to a spin-/photon-echo experiment, allows us to recover the parent BCS state. Moreover, we study the evolution of the order parameter phase ϕ in transforming the BCS superconductor to a conventional metal. Since the global phase is the conjugate variable of the density, we explicitly show how to use the dynamics of ϕ together with gauge invariance to build up the noninteracting chemical potential away from particle-hole symmetry. We further analyze the role of ϕ in restoring the gauge-invariant current response when the noninteracting Fermi liquid is approached starting from a BCS superconductor in the presence of an external vector field.}, language = {en} } @misc{CapraraDiCastroMirarchietal., author = {Caprara, Sergio and Di Castro, Carlo and Mirarchi, Giovanni and Seibold, G{\"o}tz and Grilli, Marco}, title = {Dissipation-driven strange metal behavior}, series = {Communications Physics}, journal = {Communications Physics}, number = {5}, issn = {2399-3650}, doi = {10.1038/s42005-021-00786-y}, pages = {1 -- 7}, abstract = {Anomalous metallic properties are often observed in the proximity of quantum critical points, with violation of the Fermi Liquid paradigm. We propose a scenario where, near the quantum critical point, dynamical fluctuations of the order parameter with finite correlation length mediate a nearly isotropic scattering among the quasiparticles over the entire Fermi surface. This scattering produces a strange metallic behavior, which is extended to the lowest temperatures by an increase of the damping of the fluctuations. We phenomenologically identify one single parameter ruling this increasing damping when the temperature decreases, accounting for both the linear-in-temperature resistivity and the seemingly divergent specific heat observed, e.g., in high-temperature superconducting cuprates and some heavy-fermion metals.}, language = {en} } @misc{SeiboldArpaiaYingYingetal., author = {Seibold, G{\"o}tz and Arpaia, Riccardo and Ying Ying, Peng and Fumagalli, Roberto and Braicovich, Lucio and Di Castro, Carlo and Grilli, Marco and Ghiringhelli, Giacomo Claudio and Caprara, Sergio}, title = {Strange metal behaviour from charge density fluctuations in cuprates}, series = {Communications Physics}, volume = {4}, journal = {Communications Physics}, issn = {2399-3650}, doi = {10.1038/s42005-020-00505-z}, pages = {1 -- 6}, abstract = {Besides the mechanism responsible for high critical temperature superconductivity, the grand unresolved issue of the cuprates is the occurrence of a strange metallic state above the so-called pseudogap temperature T*. Even though such state has been successfully described within a phenomenological scheme, the so-called Marginal Fermi-Liquid theory, a microscopic explanation is still missing. However, recent resonant X-ray scattering experiments identified a new class of charge density fluctuations characterized by low characteristic energies and short correlation lengths, which are related to the well-known charge density waves. These fluctuations are present over a wide region of the temperature-vs-doping phase diagram and extend well above T*. Here we investigate the consequences of charge density fluctuations on the electron and transport properties and find that they can explain the strange metal phenomenology. Therefore, charge density fluctuations are likely the long-sought microscopic mechanism underlying the peculiarities of the metallic state of cuprates.}, language = {en} } @misc{SeiboldBenfattoCastellani, author = {Seibold, G{\"o}tz and Benfatto, Lara and Castellani, Claudio}, title = {Application of the Mattis-Bardeen theory in strongly disordered superconductors}, series = {Physical Review B}, volume = {96}, journal = {Physical Review B}, number = {14}, doi = {10.1103/PhysRevB.96.144507}, pages = {144507}, abstract = {The low-energy optical conductivity of conventional superconductors is usually well described by Mattis-Bardeen (MB) theory, which predicts the onset of absorption above an energy corresponding to twice the superconducing (SC) gap parameter Δ. Recent experiments on strongly disordered superconductors have challenged the application of the MB formulas due to the occurrence of additional spectral weight at low energies below 2Δ. Here we identify three crucial items that have to be included in the analysis of optical-conductivity data for these systems: (a) the correct identification of the optical threshold in the Mattis-Bardeen theory and its relation with the gap value extracted from the measured density of states, (b) the gauge-invariant evaluation of the current-current response function needed to account for the optical absorption by SC collective modes, and (c) the inclusion into the MB formula of the energy dependence of the density of states present already above Tc. By computing the optical conductivity in the disordered attractive Hubbard model, we analyze the relevance of all these items, and we provide a compelling scheme for the analysis and interpretation of the optical data in real materials.}, language = {en} } @misc{NoatschkHofmannDabrowskietal., author = {Noatschk, Katharina and Hofmann, E. V. S. and Dabrowski, J. and Curson, N. J. and Schr{\"o}der, Thomas and Klesse, Wolfgang Matthias and Seibold, G{\"o}tz}, title = {Ge(001) surface reconstruction with Sn impurities}, series = {Surface Science}, volume = {713}, journal = {Surface Science}, doi = {10.1016/j.susc.2021.121912}, pages = {1 -- 8}, abstract = {Defects play an important role for surface reconstructions and therefore also influence the substrate growth. In this work we present a first principle calculation for the Ge(001) surface without and with tin impurities incorporated into the top surface layer. By mapping the system onto an Ising-type model, with interaction constants taken from density functional theory, the stability of the surface reconstructions under the influence of different concentrations of tin impurities is explored. This approach allows us to simulate the possible phase transitions for the different surface reconstructions including the local structure around the tin impurity atoms. In addition, we compare our theoretical results with experimental STM images on clean and Sn-doped Ge(100) surfaces.}, language = {en} } @misc{OelsenDiCioloLorenzanaetal., author = {Oelsen, E. von and Di Ciolo, A. and Lorenzana, Jos{\´e} and Seibold, G{\"o}tz and Grilli, Marco}, title = {Phonon renormalization from local and transitive electron-latticecouplings in strongly correlated systems}, language = {en} } @article{LorenzanaSeiboldOrtixetal., author = {Lorenzana, Jos{\´e} and Seibold, G{\"o}tz and Ortix, C. and Grilli, Marco}, title = {Competing orders in FeAs layers}, language = {en} } @misc{TeaCastellaniSeiboldetal., author = {Tea, C. and Castellani, Claudio and Seibold, G{\"o}tz and Benfatto, Lara}, title = {Nonrelativistic Dynamics of the Amplitude (Higgs) Mode in Superconductors}, series = {Physical Review Letters}, volume = {115}, journal = {Physical Review Letters}, issn = {1079-7114}, doi = {http://dx.doi.org/10.1103/PhysRevLett.115.157002}, pages = {157002}, language = {en} } @misc{DiCioloLorenzanaGrillietal., author = {Di Ciolo, A. and Lorenzana, Jos{\´e} and Grilli, Marco and Seibold, G{\"o}tz}, title = {Charge instabilities and electron-phonon interaction in the Hubbard-Holstein model}, series = {Physical Review B}, volume = {79}, journal = {Physical Review B}, issn = {1550-235X}, pages = {085101}, language = {en} } @misc{MirarchiSeiboldDiCastroetal., author = {Mirarchi, Giovanni and Seibold, G{\"o}tz and Di Castro, Carlo and Grilli, Marco and Caprara, Sergio}, title = {The Strange-Metal Behavior of Cuprates}, series = {Condensed Matter}, volume = {7}, journal = {Condensed Matter}, number = {1}, issn = {2410-3896}, doi = {10.3390/condmat7010029}, pages = {1 -- 17}, abstract = {Recent resonant X-ray scattering experiments on cuprates allowed to identify a new kind of collective excitations, known as charge density fluctuations, which have finite characteristic wave vector, short correlation length and small characteristic energy. It was then shown that these fluctuations provide a microscopic scattering mechanism that accounts for the anomalous transport properties of cuprates in the so-called strange-metal phase and are a source of anomalies in the specific heat. In this work, we retrace the main steps that led us to attributing a central role to charge density fluctuations in the strange-metal phase of cuprates, discuss the state of the art on the issue and provide an in-depth analysis of the contribution of charge density fluctuations to the specific heat.}, language = {en} } @misc{LemarieKamlapureBenfattoetal., author = {Lemari{\´e}, Gabriel and Kamlapure, Anand and Benfatto, Lara and Lorenzana, Jos{\´e} and Seibold, G{\"o}tz and Ganguli, S. C. and Raychaudhuri, Pratap and Castellani, Claudio}, title = {Universal scaling of the order-parameter distribution in strongly disordered superconductors}, series = {Physical Review B}, volume = {87}, journal = {Physical Review B}, number = {18}, issn = {2469-9977}, doi = {10.1103/PhysRevB.87.184509}, pages = {184509}, abstract = {We investigate theoretically and experimentally the statistical properties of the inhomogeneous order-parameter distribution (OPD) at the verge of the superconductor-insulator transition (SIT). We find within two prototype fermionic and bosonic models for disordered superconductors that one can identify a universal rescaling of the OPD. By performing scanning-tunneling microscopy experiments in three samples of NbN with increasing disorder we show that such a rescaling also describes the experimental data with excellent accuracy. These results can provide a breakthrough in our understanding of the SIT.}, language = {en} } @misc{MondalKumarChandetal., author = {Mondal, Mintu and Kumar, Sanjeev and Chand, Madhavi and Kamlapure, Anand and Saraswat, Garima and Seibold, G{\"o}tz and Benfatto, Lara and Raychaudhuri, Pratap}, title = {Role of the Vortex-Core Energy on the Berezinskii-Kosterlitz-Thouless Transition in Thin Films of NbN}, doi = {10.1103/PhysRevLett.107.217003}, language = {en} } @misc{SeiboldBeccaBuccietal., author = {Seibold, G{\"o}tz and Becca, Federico and Bucci, F. and Castellani, Claudio and Di Castro, Carlo and Grilli, Marco}, title = {Spectral properties of incommensurate charge-density wave systems}, language = {en} }