| 1. |
- Tupitsyn, Igor S., et al.
(författare)
-
Coulomb and electron-phonon interactions in metals
- 2016
-
Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 94:15
-
Tidskriftsartikel (refereegranskat)abstract
- An accurate and consistent theory of phonons in metals requires that all long-range Coulomb interactions between charged particles (electrons and ions) be treated on equal footing. So far, all attempts to deal with this nonperturbative system were relying on uncontrolled approximations in the absence of small parameters. In this paper, we develop the diagrammatic Monte Carlo approach for a two-component Coulomb system that obtains the solution to this fundamental problem in an approximation-free way by computing vertex corrections from higher-order skeleton graphs. The feasibility of the method is demonstrated by calculating the spectrum of longitudinal acoustic phonons in a simple cubic lattice, determining their sound velocity, and obtaining the phonon spectral densities by analytic continuation of the Matsubara-Green's functions. Final results are checked against the lowest-order fully self-consistent GW approximation in both adiabatic and nonadiabatic regimes.
|
|
| 2. |
- Van Houcke, Kris, et al.
(författare)
-
Dielectric function and thermodynamic properties of jellium in the GW approximation
- 2017
-
Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 95:19
-
Tidskriftsartikel (refereegranskat)abstract
- The fully self-consistent GW approximation is an established method for electronic structure calculations. Its most serious deficiency is known to be an incorrect prediction of the dielectric response. In this work, we examine the GW approximation for the homogeneous electron gas and find that problems with the dielectric response are drastically improved by enforcing the particle-number conservation law in the polarization function. We also find that previously reported data for the ground-state energy contradict each other well outside of reported error bounds. Some of these results created a false impression of how accurate the fully self-consistent GW approximation is. Our two independent implementations of the GW method agree with the data plotted in X.-Z. Yan [Phys. Rev. E 84, 016706 (2011)], thus confirming only that data set. We also present values for other key Fermi-liquid properties.
|
|
| 3. |
- Chikina, Alla, et al.
(författare)
-
Band-Order Anomaly at the gamma-Al2O3/SrTiO3 Interface Drives the Electron-Mobility Boost
- 2021
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 15:3, s. 4347-4356
-
Tidskriftsartikel (refereegranskat)abstract
- The rich functionalities of transition-metal oxides and their interfaces bear an enormous technological potential. Its realization in practical devices requires, however, a significant improvement of yet relatively low electron mobility in oxide materials. Recently, a mobility boost of about 2 orders of magnitude has been demonstrated at the spinel-perovskite gamma-Al2O3/SrTiO3 interface compared to the paradigm perovskite-perovskite LaAlO3/SrTiO3 interface. We explore the fundamental physics behind this phenomenon from direct measurements of the momentum-resolved electronic structure of this interface using resonant soft-X-ray angle-resolved photoemission. We find an anomaly in orbital ordering of the mobile electrons in gamma-Al2O3/SrTiO3 which depopulates electron states in the top SrTiO3 layer. This rearrangement of the mobile electron system pushes the electron density away from the interface, which reduces its overlap with the interfacial defects and weakens the electron-phonon interaction, both effects contributing to the mobility boost. A crystal-field analysis shows that the band order alters owing to the symmetry breaking between the spinel gamma-Al2O3 and perovskite SrTiO3. Band-order engineering, exploiting the fundamental symmetry properties, emerges as another route to boost the performance of oxide devices.
|
|
| 4. |
- Goulko, Olga, et al.
(författare)
-
Dark continuum in the spectral function of the resonant Fermi polaron
- 2016
-
Ingår i: PHYSICAL REVIEW A. - : American Institute of Physics (AIP). - 2469-9926. ; 94:5
-
Tidskriftsartikel (refereegranskat)abstract
- We present controlled numerical results for the ground-state spectral function of the resonant Fermi polaron in three dimensions. We establish the existence of a "dark continuum"-a region of anomalously low spectral weight between the narrow polaron peak and the rest of the spectral continuum. The dark continuum develops when the s-wave scattering length is of the order of the inverse Fermi wave vector, a less than or similar to 1/k(F), i.e., in the absence of a small interaction-related parameter when the spectral weight is not expected to feature a near-perfect gap structure after the polaron peak.
|
|
