Time-resolved photoemission of infinitely periodic atomic arrangements: correlation-dressed excited states of solids

Youngjae Kim,Jaedong Lee

doi:10.1038/s41524-020-00398-0

Abstract

A theory of the time-resolved photoemission spectroscopy (TRPES) is developed, which enables to explore the real-time electron dynamics of infinitely periodic crystalline solids. In the strongly correlated electron systems NiO and CuO, the early-stage dynamics of the valence band edge are found to be sharply contrasted between those in the spectra of TRPES. This provides a new dynamical insight to the Zaanen–Sawatzky–Allen (ZSA) classification scheme of correlated insulators and makes us assert that NiO dynamically behaves like the Mott–Hubbard insulator (MHI) and CuO like the charge transfer insulator (CTI). In the two-dimensional carbon layer graphene, the real-time electron dynamics of quantum-phase-dressed excited states, i.e., due to the Berry phase and the pseudospin correlation, are investigated in an unprecedented way through the time-resolved angle-resolved photoemission spectroscopy (TR-ARPES). In particular, the dephasing dynamics of optically doped electrons and holes in the massless Dirac band, accompanying a field-induced gliding of the Dirac cone, are discovered.

Highlights

Ultrafast phenomena of the optically driven transient changes in charge, spin, lattice, and orbital degrees of freedom and their crosslinks provide benchmarks for the photoinduced dynamics of a given material
The dynamical instabilities induced by the cooperative interplays among those degrees of freedom would be classified as the photoinduced phase transitions (PIPTs)[1,2], which are observed in a wide range of materials
Dependent excited states, which are dressed with the dynamical In our approach of the three-step model, step (ii) is quantum phase determined by the Berry phase and the ignored by neglecting the surface scattering, which confirms that pseudospin correlation depending on the polarizations of pump the time-dependent density functional theory (TDDFT) calculation, i.e., the time evolution of |n, q;τ〉, could be and probe pulses

Summary

INTRODUCTION

Ultrafast phenomena of the optically driven transient changes in charge, spin, lattice, and orbital degrees of freedom and their crosslinks provide benchmarks for the photoinduced dynamics of a given material. (i) NiO and CuO are strongly correlated electron systems, the modified Becke–Johnson local density approximation (mBJLDA)[26] potential is found to describe their ground states quite successfully This gives a possibility to manage the electron dynamics of the two materials in a new formalism of TRPES with time-dependent density functional theory (TDDFT) based on mBJLDA. Dependent excited states, which are dressed with the dynamical In our approach of the three-step model, step (ii) is quantum phase determined by the Berry phase and the ignored by neglecting the surface scattering, which confirms that pseudospin correlation depending on the polarizations of pump the TDDFT calculation, i.e., the time evolution of |n, q;τ〉, could be and probe pulses Those excited states in the massless Dirac band, carried out with the full translational symmetry of the material. Explored by tracing optically doped electrons and holes in the real-time domain

RESULTS

Àciþσciþ1σ iσ þ

DISCUSSION

METHODS