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Theoretical studies on subfemtosecond dynamics of excited matters

Theoretical studies on subfemtosecond dynamics of excited matters
Translated Title
들뜬 상태에서의 서브펨토초 동역학에 관한 이론적 연구
Youngjae Kim
DGIST Authors
Kim, Youngjae; Kim, HyunminLee, JaeDong
Hyunmin Kim
Issue Date
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Degree Date
Ultrafast subfemtosecond dyanmics, light and matter interactions, time-resolved photoemission spectroscopy
We introduce two aspects of the optical pulses (i.e., an audience watching the dynamics and a leading actor raising the dynamics) and demonstrate the interactions in terms of observations of real time-resolved responses and novel applications to open up the fastest electronics. First, we propose a new calculation tech-nique for the time-resolved photoemission spectroscopy that efficiently capture the real-time spectral weights of electronic structures of time-evolving single-particle Kohn-Sham orbitals in solid systems at the extremely ultrashort temporal space. It is found that the calculation can be used to explorer the non-equilibrium phase transitions of strongly correlated electron systems within the frame of the Tran-Blaha exchange potential so that it gives a new insight into the dynamical aspect of Zaanen-Sawatzky-Allen scheme in the case of excited CuO and NiO. We also introduce an appearance of pseudospin-correlated optical transitions in graphene and this would provide a chance to observe the dynamics of pseudospins in emerging materials. Second, control of electrons or their spins in the subfemtosecond time span could become a new pathway to the fastest elec-tronics or spintronics based on the light-wave-induced dynamics. We shall see the applied strain in wide-gap semiconductors is found to be a useful application to manipulate the light-wave-induced current in terms of change in effective mass as a controlling parameter. Also, we provide a smart heterojunction between 2D ferromagnetic transition metal tri-chalcogenide and non-magnetic semiconductor is shown as a petahertz spin device that generate spin filtered current or injector under the strong optical field. We believe our studies on the real-time dynamics provides an unexplored and undefined aspect induced by the optical pulses and suggests new guidance to the meaningful subfemtosecond physics.
Table Of Contents
I. Introduction 1.1 Extreme time scale 1 1.2 Ultrafast dynamics in solids 2 1.2.1 Light as an actor: pumping the dynamics 3 1.2.2 Light as an audience: probing the dynamics 3 II. Theoretical frameworks 2.1 Solving Time-dependent Schrödinger’s equations 5 2.1.1 Time-evolved two-level model 5 2.1.2 Dynamics of solid systems 9 2.2 Exact diagonalization for many-body problems 17 2.2.1 Hubbard model 17 2.2.2 Time-evolution of Hubbard system 23 2.3 Density functional theory 27 2.3.1 Kohn-Sham equation 28 2.3.2 Augmented plane wave 31 2.3.3 Local-density approximation 34 2.3.4 Modified Becke-Johnson potential 36 2.3.5 Time-dependent density functional theory 38 2.3.6 Time-resolved angle-resolved photoemission spectroscopy 42 III. Results and discussion I: correlation-dressed excited states of solids 3.1 Correlation-dressed excited states of solids 48 3.2 Correlation induced band mixing in excited states of NiO and CuO 50 3.3 Quantum-phase-dressed excited states of graphene 60 3.4 Conclusion 70 IV. Results and discussion II: Spins at petahertz time scale 4.1 Petahertz frequency control of spins 72 4.2 Model for petahertz spins 74 4.3 TDDFT results of CrPTe3/Sb(111) 83 4.4 Magnetic exchange in the heterostructure 85 4.5 Spin-orbit coupling effect 86 4.6 Conclusion 88 V. Results and discussion III: Subfemtosecond charge driving 5.1 Subfemtosecond charge driving with correlation-assisted band engineering 90 5.2 Band engineering 93 5.3 Excitonic correlation 99 5.4 Conclusion 106 VI. Summary Summary 108 VII. References References 110
Emerging Materials Science
Related Researcher
  • Author Lee, JaeDong Light and Matter Theory Laboratory
  • Research Interests Theoretical Condensed Matter Physics; Ultrafast Dynamics and Optics; Nonequilibrium Phenomena
Department of Emerging Materials ScienceThesesPh.D.

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