Laser-driven switching dynamics in phase change materials investigated by time-resolved X-ray absorption spectroscopy

Boschker, Jos E.; Wang, Rui Ning; Bragaglia, Valeria; Fons, Paul; Giussani, A.; Guyader, Löic Le; Beye, Martin; Radu, Ilie; Kolobov, Alexander V.; Holldack, K.; Calarco, Raffaella

doi:10.1080/01411594.2014.971322

Cited by 6 publications

(5 citation statements)

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“…† The calculated data are consistent with the obtained XPS and EXAFS data: when the quantity of incorporated C is larger than 5%, the generation of C–Sb bonds significantly affects the radial distribution and the difference between the length of long and short Ge–Te bonds. 32 …”

Section: Resultsmentioning

confidence: 99%

“…† The calculated data are consistent with the obtained XPS and EXAFS data: when the quantity of incorporated C is larger than 5%, the generation of C-Sb bonds signicantly affects the radial distribution and the difference between the length of long and short Ge-Te bonds. 32 Additionally, to investigate the relationship between the signicant change in chemical bonding and the modulation in structural distortion due to the incorporated carbon in detail, the charge density differences (CDDs) were extracted from our DFT calculations. The CDDs show that the chemical bonding characteristics are strongly related to the structural distortions, as shown in Fig.…”

Section: (D)-(f)mentioning

confidence: 99%

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Enhanced reliability of phase-change memory via modulation of local structure and chemical bonding by incorporating carbon in Ge₂Sb₂Te₅

et al. 2021

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Section: Resultsmentioning

confidence: 99%

Section: (D)-(f)mentioning

confidence: 99%

Enhanced reliability of phase-change memory via modulation of local structure and chemical bonding by incorporating carbon in Ge₂Sb₂Te₅

et al. 2021

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“…The control of strongly correlated electron systems via laser-induced oscillating electric fields is becoming an active area of research [1][2][3][4][5], making it important to study the dynamics of driven strongly correlated models, i.e., evolution of the system with time-dependent model parameters. The Anderson impurity model (AIM) [6], a correlated orbital coupled to a noninteracting bath, is a model of fundamental interest and is important as an auxiliary model in the dynamical mean-field approach [7][8][9] to correlated electron physics.…”

Section: Introductionmentioning

confidence: 99%

Entanglement entropy and computational complexity of the Anderson impurity model out of equilibrium: Quench dynamics

Millis

2017

Phys. Rev. B

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We study the growth of entanglement entropy in density matrix renormalization group calculations of the real-time quench dynamics of the Anderson impurity model. We find that with appropriate choice of basis, the entropy growth is logarithmic in both the interacting and noninteracting singleimpurity models. The logarithmic entropy growth is understood from a noninteracting chain model as a critical behavior separating regimes of linear growth and saturation of entropy, which correspond respectively to an overlapping and gapped energy spectra of the set of bath states. We find that a logarithmic entropy growth is the generic behavior of quenched impurity models when the bath orbitals in the matrix product state are ordered in energy. A noninteracting calculation of the doubleimpurity Anderson model supports the conclusion in the multi-impurity case. The logarithmic growth of entanglement entropy enables studies of quench dynamics to very long times.

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“…With the development of experimental technology, manipulating strongly correlated electrons using a laser-induced oscillating field is becoming possible [74,75,76]. This makes it interesting to study the driven dynamics of strongly correlated systems, i.e., evolution of systems with time-dependent Hamiltonians.…”

Section: Chaptermentioning

confidence: 99%

Computational Studies and Algorithmic Research of Strongly Correlated Materials

He¹

2019

Preprint

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Strongly correlated materials are an important topic of research in condensed matter physics. Other than ordinary solid-state physical systems, which can be well described and analyzed by the energy band theory, the electron-electron correlation effects in strongly correlated materials are far more significant. So it is necessary to develop theories and methods that are beyond the energy band theory to describe their rich and varied behaviors. Not only are there electron-electron correlations, typically the multiple degrees of freedom in strongly correlated materials, such as the charge distribution, orbital occupancies, spin orientations, and lattice structure exhibit cooperative or competitive behaviors, giving rise to rich phase diagrams and sensitive or non-perturbative responses to changes in external parameters such as temperature, strain, electromagnetic fields, etc.This thesis is divided into two parts. In the first part, we use the density functional theory (DFT) plus Hartree-Fock corrections, i.e., the DFT+U method, to calculate the equilibrium and nonequilibrium phase transitions of LuNiO 3 and VO 2 . The effect of adding U is manifested in both materials as the change of band structure in response to the change of orbital occupancies of electrons, i.e., the soft band effect. This effect bring about competitions of electrons between different orbitals by lowering the occupied orbitals and raising the empty orbitals in energy, giving rise to multiple metastable states. In the second part, we study the dynamic mean field theory (DMFT) as a beyond band-theory method. This is a Green's-function-based theory for open quantum systems. By selecting one lattice site of an interacting lattice model as an open system, the other lattice sites as the environment are equivalently replaced by a set of noninteracting orbitals according to the hybridization function, so the whole system is transformed into an Anderson impurity model (AIM). We studied how we can use the density matrix renormalization group (DMRG) method to perform real-time evolutions of the Anderson impurity model to understand the nonequilibrium dynamics of a strongly correlated lattice system.We begin in Chapter 1 with an introduction to strongly correlated materials, density functional theory (DFT) and dynamical mean-field theory (DMFT). The Kohn-Sham density functional theory and its plus U correction are discussed in detail. We also demonstrate how the dynamical mean-field theory reduces the lattice sites other than the impurity site as a set of noninteracting bath orbitals.Then in Chapters 2 and 3, we show material-related studies of LuNiO 3 as an example of rare-earth nickelates under substrate strain, and VO 2 as an example of a narrow-gap Mott insulator in a pump-probe experiment. These are two types of strongly correlated materials with localized 3d orbitals (for Ni and V). We use the DFT+U method to calculate their band structures and study the structural phase transitions in LuNiO 3 and metal-insulator transitions in both materials. The co...

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Laser-driven switching dynamics in phase change materials investigated by time-resolved X-ray absorption spectroscopy

Cited by 6 publications

References 22 publications

Enhanced reliability of phase-change memory via modulation of local structure and chemical bonding by incorporating carbon in Ge₂Sb₂Te₅

Enhanced reliability of phase-change memory via modulation of local structure and chemical bonding by incorporating carbon in Ge₂Sb₂Te₅

Entanglement entropy and computational complexity of the Anderson impurity model out of equilibrium: Quench dynamics

Computational Studies and Algorithmic Research of Strongly Correlated Materials

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Laser-driven switching dynamics in phase change materials investigated by time-resolved X-ray absorption spectroscopy

Cited by 6 publications

References 22 publications

Enhanced reliability of phase-change memory via modulation of local structure and chemical bonding by incorporating carbon in Ge2Sb2Te5

Enhanced reliability of phase-change memory via modulation of local structure and chemical bonding by incorporating carbon in Ge2Sb2Te5

Entanglement entropy and computational complexity of the Anderson impurity model out of equilibrium: Quench dynamics

Computational Studies and Algorithmic Research of Strongly Correlated Materials

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Product

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Enhanced reliability of phase-change memory via modulation of local structure and chemical bonding by incorporating carbon in Ge₂Sb₂Te₅

Enhanced reliability of phase-change memory via modulation of local structure and chemical bonding by incorporating carbon in Ge₂Sb₂Te₅