<?xml version="1.0" encoding="utf-8"?>
<export-example>
  <doc>
    <id>24511</id>
    <completedYear/>
    <publishedYear>2019</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>031042-1</pageFirst>
    <pageLast>031042-11</pageLast>
    <pageNumber/>
    <edition/>
    <issue>3</issue>
    <volume>9</volume>
    <type>articler</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2019-10-16</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Formation of Incommensurate Charge Density Waves in Cuprates</title>
    <abstract language="eng">Although charge density waves (CDWs) are omnipresent in cuprate high-temperature superconductors, they occur at significantly different wave vectors, confounding efforts to understand their formation mechanism. Here, we use resonant inelastic x-ray scattering to investigate the doping- and temperature-dependent CDW evolution in La₂₋ₓBaₓCuO₄ (x=0.115–0.155). We discover that the CDW develops in two stages with decreasing temperature. A precursor CDW with a quasicommensurate wave vector emerges first at high temperature. This doping-independent precursor CDW correlation originates from the CDW phase mode coupled with a phonon and “seeds” the low-temperature CDW with a strongly doping-dependent wave vector. Our observation reveals the precursor CDW and its phase mode as the building blocks of the highly intertwined electronic ground state in the cuprates.</abstract>
    <parentTitle language="eng">Physical Review X</parentTitle>
    <identifier type="doi">10.1103/PhysRevX.9.031042</identifier>
    <identifier type="url">https://journals.aps.org/prx/abstract/10.1103/PhysRevX.9.031042</identifier>
    <identifier type="issn">2160-3308</identifier>
    <enrichment key="BTU">an der BTU erstellt / created at BTU</enrichment>
    <enrichment key="opus.doi.autoCreate">false</enrichment>
    <enrichment key="opus.urn.autoCreate">false</enrichment>
    <author>
      <firstName>Hu</firstName>
      <lastName>Miao</lastName>
    </author>
    <submitter>
      <firstName>Katrin</firstName>
      <lastName>Gregor</lastName>
    </submitter>
    <author>
      <firstName>Roberto</firstName>
      <lastName>Fumagalli</lastName>
    </author>
    <author>
      <firstName>M.</firstName>
      <lastName>Rossi</lastName>
    </author>
    <author>
      <firstName>José</firstName>
      <lastName>Lorenzana</lastName>
    </author>
    <author>
      <firstName>Götz</firstName>
      <lastName>Seibold</lastName>
    </author>
    <author>
      <firstName>Flora</firstName>
      <lastName>Yakhou-Harris</lastName>
    </author>
    <author>
      <firstName>K.</firstName>
      <lastName>Kummer</lastName>
    </author>
    <author>
      <firstName>Nicholas B.</firstName>
      <lastName>Brookes</lastName>
    </author>
    <author>
      <firstName>G. D.</firstName>
      <lastName>Gu</lastName>
    </author>
    <author>
      <firstName>Lucio</firstName>
      <lastName>Braicovich</lastName>
    </author>
    <author>
      <firstName>Giacomo Claudio</firstName>
      <lastName>Ghiringhelli</lastName>
    </author>
    <author>
      <firstName>M. P. M.</firstName>
      <lastName>Dean</lastName>
    </author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Research Areas  Charge density waves</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Electrical Properties</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Cuprates</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Strongly correlated systems</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Resonant inelastic x-ray scattering</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Superconductivity</value>
    </subject>
    <collection role="institutes" number="1501">FG Computational Physics</collection>
  </doc>
  <doc>
    <id>26111</id>
    <completedYear/>
    <publishedYear>2020</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber>15</pageNumber>
    <edition/>
    <issue>14</issue>
    <volume>102</volume>
    <type>articler</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2020-10-06</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Nonequilibrium dynamics from BCS to the bosonic limit</title>
    <abstract language="eng">Within the time-dependent Gutzwiller approximation applied to the negative-U Hubbard model, we investigate the dynamics of a superconductor after an interaction quench for different values of the final interaction from weak to strong coupling. The equilibrium BCS-BEC crossover becomes a sharp transition in the out-of-equilibrium dynamics between weak- and strong-coupling dynamical phases. Two different frequencies (ΩJ&lt;ΩU) dominate the order parameter dynamics. In the weak coupling phase, ΩJ follows twice the asymptotic average value of the gap (ΩJ≈2Δ∞) and ΩU is much larger but hardy visible in the anomalous density. At long times the BCS dynamics is recovered but surprisingly differences remain during the transient phase. In the strong coupling phase, the dynamics decouples from the asymptotic value of the order parameter except at exactly half filling and close to the dynamical transition where ΩU≈2Δ∞. The out-of-equilibrium transient spectral density and optical conductivity are presented and discussed in relation to pump probe experiments. Both ΩJ and ΩU give rise to a complex structure of self-driven slow Rabi oscillations which are visible in the nonequilibrium optical conductivity where also sidebands appear due to the modulation of the double occupancy by superconducting amplitude oscillations. Analogous results apply to CDW and SDW systems. Our results show that in systems with long coherence times, pump-probe experiments allow us to characterize the regime (BCS vs preformed pairs) through very specific out-of-equilibrium fingerprints.</abstract>
    <parentTitle language="eng">Physical Review B</parentTitle>
    <identifier type="doi">10.1103/PhysRevB.102.144502</identifier>
    <identifier type="url">https://journals.aps.org/prb/abstract/10.1103/PhysRevB.102.144502</identifier>
    <identifier type="issn">2469-9969</identifier>
    <enrichment key="BTU">an der BTU erstellt / created at BTU</enrichment>
    <enrichment key="Artikelnummer">144502</enrichment>
    <enrichment key="opus.doi.autoCreate">false</enrichment>
    <enrichment key="opus.urn.autoCreate">false</enrichment>
    <enrichment key="Fprofil">1 Energiewende und Dekarbonisierung / Energy Transition and Decarbonisation</enrichment>
    <enrichment key="Fprofil">4 Künstliche Intelligenz und Sensorik / Artificial Intelligence and Sensor Technology</enrichment>
    <author>
      <firstName>Götz</firstName>
      <lastName>Seibold</lastName>
    </author>
    <submitter>
      <firstName>Katrin</firstName>
      <lastName>Gregor</lastName>
    </submitter>
    <author>
      <firstName>Jose</firstName>
      <lastName>Lorenzana</lastName>
    </author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>BEC-BCS crossover</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Superconductivity fluctuations</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Superconductivity</value>
    </subject>
    <collection role="institutes" number="1501">FG Computational Physics</collection>
  </doc>
  <doc>
    <id>28899</id>
    <completedYear/>
    <publishedYear>2022</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>184513-1</pageFirst>
    <pageLast>184513-14</pageLast>
    <pageNumber/>
    <edition/>
    <issue>18</issue>
    <volume>105</volume>
    <type>articler</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2022-05-24</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Adiabatic transition from a BCS superconductor to a Fermi liquid and phase dynamics</title>
    <abstract language="eng">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.</abstract>
    <parentTitle language="eng">Physical Review B</parentTitle>
    <identifier type="url">https://journals.aps.org/prb/abstract/10.1103/PhysRevB.105.184513</identifier>
    <identifier type="doi">10.1103/PhysRevB.105.184513</identifier>
    <identifier type="issn">2469-9969</identifier>
    <enrichment key="BTU">an der BTU erstellt / created at BTU</enrichment>
    <enrichment key="opus.source">publish</enrichment>
    <enrichment key="Artikelnummer">184513</enrichment>
    <enrichment key="Fprofil">1 Energiewende und Dekarbonisierung / Energy Transition and Decarbonisation</enrichment>
    <enrichment key="Fprofil">4 Künstliche Intelligenz und Sensorik / Artificial Intelligence and Sensor Technology</enrichment>
    <author>
      <firstName>Götz</firstName>
      <lastName>Seibold</lastName>
    </author>
    <submitter>
      <firstName>Katrin</firstName>
      <lastName>Gregor</lastName>
    </submitter>
    <author>
      <firstName>Claudio</firstName>
      <lastName>Castellani</lastName>
    </author>
    <author>
      <firstName>José</firstName>
      <lastName>Lorenzana</lastName>
    </author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Superconductivity</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Nonequilibrium systems</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Adiabatic approximation</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>BCS theory</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Gauge symmetries</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Variational approach</value>
    </subject>
    <collection role="institutes" number="1501">FG Computational Physics</collection>
  </doc>
  <doc>
    <id>34075</id>
    <completedYear/>
    <publishedYear>2024</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>1</pageFirst>
    <pageLast>12</pageLast>
    <pageNumber/>
    <edition/>
    <issue>4</issue>
    <volume>9</volume>
    <type>articler</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2024-09-30</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Undamped higgs modes in strongly interacting superconductors</title>
    <abstract language="eng">In superconductors, gauge 𝑈(1) symmetry is spontaneously broken. According to Goldstone’s theorem, this breaking of a continuous symmetry establishes the existence of the Bogoliubov phase mode while the gauge-invariant response also includes the amplitude fluctuations of the order parameter. The latter, which are also termed ‘Higgs’ modes in analogy with the standard model, appear at the energy of the spectral gap 2Δ, when the superconducting ground state is evaluated within the weak-coupling BCS theory, and, therefore, are damped. Previously, we have shown that, within the time-dependent Gutzwiller approximation (TDGA), Higgs modes appear inside the gap with a finite binding energy relative to the quasiparticle continuum. Here, we show that the binding energy of the Higgs mode becomes exponentially small in the weak-coupling limit converging to the BCS solution. On the other hand, well-defined undamped amplitude modes exist in strongly coupled superconductors when the interaction energy becomes of the order of the bandwidth.</abstract>
    <parentTitle language="eng">Condens Matter</parentTitle>
    <identifier type="doi">10.3390/condmat9040038</identifier>
    <enrichment key="BTU">an der BTU erstellt / created at BTU</enrichment>
    <enrichment key="Artikelnummer">38</enrichment>
    <enrichment key="Publikationsweg">Open Access</enrichment>
    <enrichment key="opus.source">publish</enrichment>
    <enrichment key="opus.doi.autoCreate">false</enrichment>
    <enrichment key="opus.urn.autoCreate">false</enrichment>
    <enrichment key="Fprofil">1 Energiewende und Dekarbonisierung / Energy Transition and Decarbonisation</enrichment>
    <enrichment key="Fprofil">4 Künstliche Intelligenz und Sensorik / Artificial Intelligence and Sensor Technology</enrichment>
    <author>
      <firstName>José</firstName>
      <lastName>Lorenzana</lastName>
    </author>
    <submitter>
      <firstName>Katrin</firstName>
      <lastName>Gregor</lastName>
    </submitter>
    <author>
      <firstName>Götz</firstName>
      <lastName>Seibold</lastName>
    </author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>superconductivity</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>time-dependent Gutzwiller</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>collective modes</value>
    </subject>
    <collection role="institutes" number="1501">FG Computational Physics</collection>
  </doc>
  <doc>
    <id>32349</id>
    <completedYear/>
    <publishedYear>2024</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>026501-1</pageFirst>
    <pageLast>026501-8</pageLast>
    <pageNumber/>
    <edition/>
    <issue>2</issue>
    <volume>132</volume>
    <type>articler</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2024-01-10</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Long-Lived Higgs Modes in Strongly Correlated Condensates</title>
    <abstract language="eng">We investigate order parameter fluctuations in the Hubbard model within a time-dependent Gutzwiller approach. While in the weak coupling limit we find that the amplitude fluctuations are short-lived due to a degeneracy with the energy of the edge of the quasiparticle continua (and in agreement with Hartree-Fock+RPA theory), these are shifted below the edge upon increasing the interaction. Our calculations therefore predict undamped amplitude (Higgs) oscillations of the order parameter in strongly coupled superconductors, cold atomic fermion condensates, and strongly interacting charge- and spin-density wave systems. We propose an experimental realization for the detection of the spin-type Higgs mode in undoped cuprates and related materials where, due to the Dzyaloshinsky-Moriya interaction, it can couple to an out-of-plane ferromagnetic excitation that is visible via the Faraday effect.</abstract>
    <parentTitle language="eng">Physical Review Letters</parentTitle>
    <identifier type="url">https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.132.026501</identifier>
    <identifier type="doi">10.1103/PhysRevLett.132.026501</identifier>
    <identifier type="issn">0031-9007</identifier>
    <enrichment key="BTU">an der BTU erstellt / created at BTU</enrichment>
    <enrichment key="Artikelnummer">026501</enrichment>
    <enrichment key="Publikationsweg">Open Access</enrichment>
    <enrichment key="opus.source">publish</enrichment>
    <enrichment key="Fprofil">1 Energiewende und Dekarbonisierung / Energy Transition and Decarbonisation</enrichment>
    <enrichment key="Fprofil">4 Künstliche Intelligenz und Sensorik / Artificial Intelligence and Sensor Technology</enrichment>
    <author>
      <firstName>Jose</firstName>
      <lastName>Lorenzana</lastName>
    </author>
    <submitter>
      <firstName>Katrin</firstName>
      <lastName>Gregor</lastName>
    </submitter>
    <author>
      <firstName>Götz</firstName>
      <lastName>Seibold</lastName>
    </author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Magnetism</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Quasiparticles &amp; collective excitations</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Spin dynamics</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Superconducting order parameter</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Superconductivity</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Antiferromagnets</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Atomic gases</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>High-temperature superconductors</value>
    </subject>
    <collection role="institutes" number="1501">FG Computational Physics</collection>
  </doc>
</export-example>
