scholarly journals Effect of quasiparticle excitations and exchange-correlation in Coulomb drag in graphene

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Rajveer Fandan ◽  
Jorge Pedrós ◽  
Francisco Guinea ◽  
Alberto Boscá ◽  
Fernando Calle
Keyword(s):  
Room Temperature ◽  
Correlation Effects ◽  
Many Body ◽  
Phonon Modes ◽  
Coulomb Drag ◽  
Exchange Correlation ◽  
Layer Graphene ◽  
Maximum Value ◽  
Zero Layer ◽  
Exchange And Correlation

AbstractCoulomb drag in double layer graphene systems separated by an h-BN interlayer allows probing of the electron-electron interactions in the effective limit of zero layer separation. Although these interactions can be influenced by plasmons, phonons and exchange and correlation effects, these excitations have never been studied altogether, missing the effects of their coupling on the drag physics. Here we study theoretically the effects of these quasiparticles and their coupling, including also the effects of the electronic exchange and correlation, and demonstrate that the drag resistivity can attain a maximum value at room temperature and beyond, where hybridized plasmon-phonon modes contribute significantly. In particular, the hybridization of the plasmons with the hyperbolic phonons of h-BN, confined within the reststrahlen bands, enhance the drag resistivity. This study paves the way for the exploration of novel many-body physics phenomena in systems coupled through emerging 2D hyperbolic materials.

scholarly journals Many-body exchange-correlation effects in graphene

2008 ◽  
Vol 40 (5) ◽  
pp. 1653-1655 ◽  
Author(s):  
E.H. Hwang ◽  
Ben Yu-Kuang Hu ◽  
S. Das Sarma
Keyword(s):  
Correlation Effects ◽  
Many Body ◽  
Exchange Correlation

scholarly journals Ultrafast melting and recovery of collective order in the excitonic insulator Ta2NiSe5

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hope M. Bretscher ◽  
Paolo Andrich ◽  
Prachi Telang ◽  
Anupam Singh ◽  
Luminita Harnagea ◽  
...  
Keyword(s):  
Ground State ◽  
Room Temperature ◽  
Near Infrared ◽  
Infrared Range ◽  
Many Body ◽  
Phonon Modes ◽  
Equilibrium Dynamics ◽  
Excitonic Insulator ◽  
Optical Signature ◽  
The Status

AbstractThe layered chalcogenide Ta2NiSe5 has been proposed to host an excitonic condensate in its ground state, a phase that could offer a unique platform to study and manipulate many-body states at room temperature. However, identifying the dominant microscopic contribution to the observed spontaneous symmetry breaking remains challenging, perpetuating the debate over the ground state properties. Here, using broadband ultrafast spectroscopy we investigate the out-of-equilibrium dynamics of Ta2NiSe5 and demonstrate that the transient reflectivity in the near-infrared range is connected to the system’s low-energy physics. We track the status of the ordered phase using this optical signature, establishing that high-fluence photoexcitations can suppress this order. From the sub-50 fs quenching timescale and the behaviour of the photoinduced coherent phonon modes, we conclude that electronic correlations provide a decisive contribution to the excitonic order formation. Our results pave the way towards the ultrafast control of an exciton condensate at room temperature.

scholarly journals Properties of Silicone Rubber-Based Composites Reinforced with Few-Layer Graphene and Iron Oxide or Titanium Dioxide

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1550
Author(s):  
Vineet Kumar ◽  
Anuj Kumar ◽  
Minseok Song ◽  
Dong-Joo Lee ◽  
Sung-Soo Han ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Titanium Dioxide ◽  
Iron Oxide ◽  
Stress Relaxation ◽  
Silicone Rubber ◽  
Room Temperature ◽  
Relaxation Rates ◽  
Layer Graphene ◽  
Few Layer Graphene ◽  
Mechanical Actuation

The increasing demand for polymer composites with novel or improved properties requires novel fillers. To meet the challenges posed, nanofillers such as graphene, carbon nanotubes, and titanium dioxide (TiO2) have been used. In the present work, few-layer graphene (FLG) and iron oxide (Fe3O4) or TiO2 were used as fillers in a room-temperature-vulcanized (RTV) silicone rubber (SR) matrix. Composites were prepared by mixing RTV-SR with nanofillers and then kept for vulcanization at room temperature for 24 h. The RTV-SR composites obtained were characterized with respect to their mechanical, actuation, and magnetic properties. Fourier-transform infrared spectroscopy (FTIR) analysis was performed to investigate the composite raw materials and finished composites, and X-ray photoelectron spectroscopy (XPS) analysis was used to study composite surface elemental compositions. Results showed that mechanical properties were improved by adding fillers, and actuation displacements were dependent on the type of nanofiller used and the applied voltage. Magnetic stress-relaxation also increased with filler amount and stress-relaxation rates decreased when a magnetic field was applied parallel to the deformation axes. Thus, this study showed that the inclusion of iron oxide (Fe3O4) or TiO2 fillers in RTV-SR improves mechanical, actuation, and magnetic properties.

scholarly journals Application of time-dependent current-density-functional theory to nonlocal exchange-correlation effects in polymers

2003 ◽  
Vol 118 (3) ◽  
pp. 1044-1053 ◽  
Author(s):  
M. van Faassen ◽  
P. L. de Boeij ◽  
R. van Leeuwen ◽  
J. A. Berger ◽  
J. G. Snijders
Keyword(s):  
Density Functional Theory ◽  
Current Density ◽  
Density Functional ◽  
Time Dependent ◽  
Correlation Effects ◽  
Functional Theory ◽  
Exchange Correlation

Exchange and correlation effects in strained-layer semiconductor quantum wells

2004 ◽  
Vol 241 (5) ◽  
pp. 1046-1052
Author(s):  
C. Tong ◽  
M. R. Kim ◽  
S. K. Kim ◽  
B. H. Han ◽  
J. K. Rhee
Keyword(s):  
Quantum Wells ◽  
Correlation Effects ◽  
Strained Layer ◽  
Semiconductor Quantum Wells ◽  
Exchange And Correlation
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