Many-Body Interactions in Nanoscale Materials by Angle-Resolved Photoemission Spectroscopy

2010 ◽  
pp. 169-209
Author(s):  
Eli Rotenberg
2014 ◽  
Vol 171 ◽  
pp. 311-321 ◽  
Author(s):  
Isabella Gierz ◽  
Stefan Link ◽  
Ulrich Starke ◽  
Andrea Cavalleri

We have used time- and angle-resolved photoemission spectroscopy (tr-ARPES) to assess the influence of many-body interactions on the Dirac carrier dynamics in graphene. From the energy-dependence of the measured scattering rates we directly determine the imaginary part of the self-energy, visualizing the existence of a relaxation bottleneck associated with electron–phonon coupling. A comparison with static line widths obtained by high-resolution ARPES indicates that the dynamics of photo-excited carriers in graphene are solely determined by the equilibrium self-energy. Furthermore, the subtle interplay of different many-body interactions in graphene may allow for carrier multiplication, where the absorption of a single photon generates more than one electron-hole pair via impact ionization. We find that, after photo-excitation, the number of carriers in the conduction band along the ΓK-direction keeps increasing for about 40 fs after the pump pulse is gone. A definite proof of carrier multiplication in graphene, however, requires a more systematic study, carefully taking into account the contribution of momentum relaxation on the measured rise time.


2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Qiyang Lu ◽  
Henrique Martins ◽  
Juhan Matthias Kahk ◽  
Gaurab Rimal ◽  
Seongshik Oh ◽  
...  

AbstractWhen a three-dimensional material is constructed by stacking different two-dimensional layers into an ordered structure, new and unique physical properties can emerge. An example is the delafossite PdCoO2, which consists of alternating layers of metallic Pd and Mott-insulating CoO2 sheets. To understand the nature of the electronic coupling between the layers that gives rise to the unique properties of PdCoO2, we revealed its layer-resolved electronic structure combining standing-wave X-ray photoemission spectroscopy and ab initio many-body calculations. Experimentally, we have decomposed the measured VB spectrum into contributions from Pd and CoO2 layers. Computationally, we find that many-body interactions in Pd and CoO2 layers are highly different. Holes in the CoO2 layer interact strongly with charge-transfer excitons in the same layer, whereas holes in the Pd layer couple to plasmons in the Pd layer. Interestingly, we find that holes in states hybridized across both layers couple to both types of excitations (charge-transfer excitons or plasmons), with the intensity of photoemission satellites being proportional to the projection of the state onto a given layer. This establishes satellites as a sensitive probe for inter-layer hybridization. These findings pave the way towards a better understanding of complex many-electron interactions in layered quantum materials.


2020 ◽  
Vol 117 (46) ◽  
pp. 28596-28602
Author(s):  
Jianqiang Sky Zhou ◽  
Lucia Reining ◽  
Alessandro Nicolaou ◽  
Azzedine Bendounan ◽  
Kari Ruotsalainen ◽  
...  

Interaction effects can change materials properties in intriguing ways, and they have, in general, a huge impact on electronic spectra. In particular, satellites in photoemission spectra are pure many-body effects, and their study is of increasing interest in both experiment and theory. However, the intrinsic spectral function is only a part of a measured spectrum, and it is notoriously difficult to extract this information, even for simple metals. Our joint experimental and theoretical study of the prototypical simple metal aluminum demonstrates how intrinsic satellite spectra can be extracted from measured data using angular resolution in photoemission. A nondispersing satellite is detected and explained by electron–electron interactions and the thermal motion of the atoms. Additional nondispersing intensity comes from the inelastic scattering of the outgoing photoelectron. The ideal intrinsic spectral function, instead, has satellites that disperse both in energy and in shape. Theory and the information extracted from experiment describe these features with very good agreement.


2020 ◽  
Author(s):  
Marc Riera ◽  
Alan Hirales ◽  
Raja Ghosh ◽  
Francesco Paesani

<div> <div> <div> <p>Many-body potential energy functions (PEFs) based on the TTM-nrg and MB-nrg theoretical/computational frameworks are developed from coupled cluster reference data for neat methane and mixed methane/water systems. It is shown that that the MB-nrg PEFs achieve subchemical accuracy in the representation of individual many-body effects in small clusters and enables predictive simulations from the gas to the liquid phase. Analysis of structural properties calculated from molecular dynamics simulations of liquid methane and methane/water mixtures using both TTM-nrg and MB-nrg PEFs indicates that, while accounting for polarization effects is important for a correct description of many-body interactions in the liquid phase, an accurate representation of short-range interactions, as provided by the MB-nrg PEFs, is necessary for a quantitative description of the local solvation structure in liquid mixtures. </p> </div> </div> </div>


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