| 1. |
- Abdullaev, F. Kh., et al.
(författare)
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Nonlinearity managed vector solitons
- 2023
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Ingår i: Physics Letters A. - : Elsevier. - 0375-9601 .- 1873-2429. ; 491
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Tidskriftsartikel (refereegranskat)abstract
- The evolution of vector solitons under nonlinearity management is studied. The averaged over strong and rapid modulations in time of the inter-species interactions vector Gross-Pitaevskii equation (GPE) is derived. The averaging gives the appearance of the effective nonlinear quantum pressure depending on the population of the other component. Using this system of equations, the existence and stability of the vector solitons under the action of the strong nonlinearity management (NM) is investigated. Using a variational approach the parameters of NM vector solitons are found. The numerical simulations of the full time-dependent coupled GPE confirms the theoretical predictions.
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| 2. |
- Bilal, Muhammad, et al.
(författare)
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DFT insights into surface properties of anti-perovskite 3D topological crystalline insulators : A case study of (001) surfaces of Ca3SnO
- 2021
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Ingår i: Physics Letters A. - : Elsevier. - 0375-9601 .- 1873-2429. ; 408
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Tidskriftsartikel (refereegranskat)abstract
- In this letter density functional theory calculations are used for investigating the structural, energetic and electronic properties of CaSn- and Ca2O-terminated (001) surfaces of anti-perovskite Ca3SnO. Our calculations indicate larger structural changes in case of the CaSn-terminated (001) surface of Ca3SnO, however, both CaSn- and Ca2O-terminated surfaces of Ca3SnO are found to be energetically stable. The electronic properties of (001) surfaces of Ca3SnO are examined by taking spin-orbit coupling into account. Comparison of the simulated results of electronic properties for the two (001) surfaces of Ca3SnO with experimentally reported hole carrier densities observed in p-type polycrystalline samples show good agreement.
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| 3. |
- Freire, Hermann, et al.
(författare)
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Thermoelectric and thermal properties of the weakly disordered non-Fermi liquid phase of Luttinger semimetals
- 2021
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Ingår i: Physics Letters A. - : Elsevier BV. - 0375-9601 .- 1873-2429. ; 407
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Tidskriftsartikel (refereegranskat)abstract
- We compute the thermoelectric and thermal transport coefficients in the weakly disordered non-Fermi liquid phase of the Luttinger semimetals at zero doping, where the decay rate associated with the (strong) Coulomb interactions is much larger than the electron-impurity scattering rate. To this end, we implement the Mori-Zwanzig memory matrix method, that does not rely on the existence of long-lived quasiparticles in the system. We find that the thermal conductivity at zero electric field scales as (kappa) over bar similar to T-n (with 0 less than or similar to n less than or similar to 1) at low temperatures, whereas the thermoelectric coefficient has the temperature dependence given by alpha similar to T-p (with 1/2 less than or similar to p less than or similar to 3/2). These unconventional properties turn out to be key signatures of this long sought-after non-Fermi liquid state in the Luttinger semimetals, which is expected to emerge in strongly correlated spin-orbit coupled materials like the pyrochlore iridates. Finally, our results indicate that these materials might be good candidates for achieving high figure-of-merit for thermoelectric applications.
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| 4. |
- Johansson, Magnus
(författare)
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Topological edge breathers in a nonlinear Su-Schrieffer-Heeger lattice
- 2023
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Ingår i: Physics Letters A. - : ELSEVIER. - 0375-9601 .- 1873-2429. ; 458
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Tidskriftsartikel (refereegranskat)abstract
- We show the existence of breathing edge modes in the Su-Schrieffer-Heeger model with cubic (Kerr) on-site nonlinearity, bifurcating from stationary edge solitons with propagation constant inside the topological gap of the linear model. These edge breathers are exact solutions to the nonlinear equations of motion, with time-periodic intensity oscillations and tails exponentially decaying from the edge. They bifurcate from two localized internal eigenmodes of the stationary edge soliton, having eigenfrequencies inside the topological gap and all higher harmonics above the linear spectrum. Numerical Floquet analysis for solutions obtained from a Newton scheme shows that edge breathers may be linearly stable even in regimes of large-amplitude oscillations, mainly manifested as time-periodic power exchange between the edge site and its next-nearest neighbor. (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
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| 5. |
- Liberman, Michael A.
(författare)
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Hydrogen atom in a magnetic field as an exactly solvable system without dynamical symmetries?
- 2022
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Ingår i: Physics Letters A. - : Elsevier BV. - 0375-9601 .- 1873-2429. ; 445
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Tidskriftsartikel (refereegranskat)abstract
- According to the generally accepted classification, there are supersymmetric superintegrable systems for which the Schrödinger equation is separable in more than one coordinate system and which admit an exact solution. A classic example of a superintegrable system is a hydrogen atom. It is believed that the converse is also true: an exactly solvable system has many integrals of motion corresponding to the separation constants of the Schrödinger equation in more than one coordinate system, which also means a high symmetry group of the system. It is shown that the existence of an exact solution for a hydrogen atom in an arbitrary strong uniform magnetic field apparently contradicts this classification.
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| 6. |
- Mandal, Ipsita
(författare)
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Robust marginal Fermi liquid in birefringent semimetals
- 2021
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Ingår i: Physics Letters A. - : Elsevier BV. - 0375-9601 .- 1873-2429. ; 418
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the interplay of Coulomb interactions and correlated disorder in pseudospin-3/2 semimetals, which exhibit birefringent spectra in the absence of interactions. Coulomb interactions drive the system to a marginal Fermi liquid, both for the two-dimensional (2d) and three-dimensional (3d) cases. Short-ranged correlated disorder in 2d, or a power-law correlated disorder 3d, has the same engineering dimension as the Coulomb term, in a renormalization group (RG) sense. In order to analyze the combined effects of these two kinds of interactions, we apply a dimensional regularization scheme and derive the RG flow equations. The results show that the marginal Fermi liquid phase is robust against disorder.
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| 7. |
- Sundqvist, Bertil
(författare)
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Correlation between weak localization effects and resistivity saturation in dilute Ti-Al alloys
- 2021
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Ingår i: Physics Letters A. - : Elsevier. - 0375-9601 .- 1873-2429. ; 400
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Tidskriftsartikel (refereegranskat)abstract
- Resistivity saturation in Ti-Al alloys has been studied by fitting empirical functions of temperature, T, to 20 sets of literature data. By replacing the commonly used temperature-independent saturation term by a term in T−1/2, to model weak localization effects at high temperature, the quality of the fits improved significantly and physically acceptable values were obtained for the fitted parameters. A linear correlation was found between the fitted high-T weak localization parameters and experimental data for the corresponding low-T weak localization conduction terms. No such correlation could be detected when using constant saturation terms. The results suggest that weak localization is a possible cause for resistivity saturation in Ti-Al alloys.
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| 8. |
- Yang, Xiao-Yong, et al.
(författare)
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Mechanical, electronic and thermodynamic properties of crystalline molecular hydrogen at high pressure
- 2023
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Ingår i: Physics Letters A. - : Elsevier. - 0375-9601 .- 1873-2429. ; 483
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Tidskriftsartikel (refereegranskat)abstract
- Solid molecular hydrogen exhibits a rich variety of unique properties, including insulator-to-metal transition. However, the specific structure of phase III remains unclear. Experimental evidence suggests high-pressure hydrogen shows a hexagonal close-packed lattice. Therefore, as a potential candidate for phase III, the structure, energetic, mechanical, electronic, and thermodynamic properties of 22 structure are systemically studied. It is found phase III with P6122 space group is both mechanically and thermodynamically stable within the pressure range of 120∼300 GPa. Besides, we observed significant enhancements in the bulk modulus, shear modulus, and Young's modulus. The band structures exhibit a transition from topological insulator to topological semiconductor and eventually to a Wely semimetal as the pressure increases. The electron density accumulates between pseudo “H2” molecules in the insulating phase but it partly channels into the interlayer space in the semimetallic phase. Phase III with P6122 structure is barely explored previously in solid hydrogen, therefore, we believe our present investigation contributes valuable insights towards understanding the behavior of metallic hydrogen.
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