Ultrafast Spectroscopy of Carrier and Spin Dynamics in Hybrid Perovskites

2019 ◽  
Author(s):  
Felix Deschler
Keyword(s):  
Ultrafast Spectroscopy ◽  
Spin Dynamics

scholarly journals Deciphering asymmetric charge transfer at transition metal dichalcogenide–graphene interface by helicity-resolved ultrafast spectroscopy

2021 ◽  
Vol 7 (34) ◽  
pp. eabg2999
Author(s):  
Hongzhi Zhou ◽  
Yuzhong Chen ◽  
Haiming Zhu
Keyword(s):  
Charge Transfer ◽  
Transition Metal ◽  
Ultrafast Spectroscopy ◽  
Spin Dynamics ◽  
Hole Injection ◽  
Transition Metal Dichalcogenide ◽  
Transfer Processes ◽  
Spin Polarized ◽  
Graphene Interface ◽  
Interfacial Charge

Transition metal dichalcogenide (TMD)/graphene (Gr) heterostructures constitute a key component for two-dimensional devices. The operation of TMD/Gr devices relies on interfacial charge/energy transfer processes, which remains unclear and challenging to unravel. Fortunately, the coupled spin and valley index in TMDs adds a new degree of freedom to the charges and, thus, another dimension to spectroscopy. Here, by helicity-resolved ultrafast spectroscopy, we find that photoexcitation in TMDs transfers to graphene by asynchronous charge transfer, with one type of charge transferring in the order of femtoseconds and the other in picoseconds. The rate correlates well with energy offset between TMD and graphene, regardless of compositions and charge species. Spin-polarized hole injection or long-lived polarized hole can be achieved with deliberately designed heterostructures. This study shows helicity-resolved ultrafast spectroscopy as a powerful and facile approach to reveal the fundamental and complex charge/spin dynamics in TMD-based heterostructures, paving the way toward valleytronic and optoelectronic applications.

Ultrafast Spectroscopy of Chromophores

2012 ◽  
Author(s):  
Eduardo Arias ◽  
Ivana Moggio ◽  
Ronald F. Ziolo
Keyword(s):  
Ultrafast Spectroscopy

The Damping Term, from First Principles

2017 ◽  
Author(s):  
Olle Eriksson ◽  
Anders Bergman ◽  
Lars Bergqvist ◽  
Johan Hellsvik
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Spin Dynamics ◽  
Damping Term ◽  
Functional Theory ◽  
Basic Principles ◽  
Sham Equation ◽  
Damping Parameter ◽  
Simulation Cell

In the previous chapters we described the basic principles of density functional theory, gave examples of how accurate it is to describe static magnetic properties in general, and derived from this basis the master equation for atomistic spin-dynamics; the SLL (or SLLG) equation. However, one term was not described in these chapters, namely the damping parameter. This parameter is a crucial one in the SLL (or SLLG) equation, since it allows for energy and angular momentum to dissipate from the simulation cell. The damping parameter can be evaluated from density functional theory, and the Kohn-Sham equation, and it is possible to determine its value experimentally. This chapter covers in detail the theoretical aspects of how to calculate theoretically the damping parameter. Chapter 8 is focused, among other things, on the experimental detection of the damping, using ferromagnetic resonance.

Strong Coupling of Electron and Nuclear Spins: Outlook and Prospects

2018 ◽  
Author(s):  
M. M. Glazov
Keyword(s):  
Energy Spectrum ◽  
Charge Carrier ◽  
Strong Coupling ◽  
Nuclear Spin ◽  
Spin Dynamics ◽  
Spin Polaron ◽  
Nuclear Spins ◽  
Deep Impurity ◽  
Impurity Centers ◽  
Ordered State

In this chapter, some prospects in the field of electron and nuclear spin dynamics are outlined. Particular emphasis is put ona situation where the hyperfine interaction is so strong that it leads to a qualitative rearrangement of the energy spectrum resulting in the coherent excitation transfer between the electron and nucleus. The strong coupling between the spin of the charge carrier and of the nucleus is realized, for example in the case of deep impurity centers in semiconductors or in isotopically purified systems. We also discuss the effect of the nuclear spin polaron, that is ordered state, formation at low enough temperatures of nuclear spins, where the orientation of the carrier spin results in alignment of the spins of nucleus interacting with the electron or hole.

Electron Spin Decoherence by Nuclei

2018 ◽  
Author(s):  
M. M. Glazov
Keyword(s):  
Electron Spin ◽  
Spin Dynamics ◽  
Magnetic Moments ◽  
Host Lattice ◽  
Spin Model ◽  
Relaxation Processes ◽  
Nuclear Spins ◽  
Model Calculations ◽  
Spin Decoherence ◽  
Quantum Mechanical Approach

The discussion of the electron spin decoherence and relaxation phenomena via the hyperfine interaction with host lattice spins is presented here. The spin relaxation processes processes limit the conservation time of spin states as well as the response time of the spin system to external perturbations. The central spin model, where the spin of charge carrier interacts with the bath of nuclear spins, is formulated. We also present different methods to calculate the spin dynamics within this model. Simple but physically transparent semiclassical treatment where the nuclear spins are considered as largely static classical magnetic moments is followed by more advanced quantum mechanical approach where the feedback of electron spin dynamics on the nuclei is taken into account. The chapter concludes with an overview of experimental data and its comparison with model calculations.

Beta-NMR and Basic Processes in Spin Dynamics

2021 ◽  
Author(s):  
F. S. Dzheparov ◽  
A. D. Gulko ◽  
D. V. Lvov
Keyword(s):  
Spin Dynamics

scholarly journals Collective spin dynamics under dissipative spin Hall torque

2021 ◽  
Vol 118 (3) ◽  
pp. 032406
Author(s):  
Yaroslav Tserkovnyak ◽  
Eran Maniv ◽  
James G. Analytis
Keyword(s):  
Spin Dynamics
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