Essays about: "lattice"

Showing result 6 - 10 of 280 essays containing the word lattice.

1. 6. Towards a setup for narrowband terahertz generation through difference-frequency mixing of chirped ultrashort pulses

   University essay from Lunds universitet/Atomfysik; Lunds universitet/Fysiska institutionen

   Author : Isa Clementsson; [2023]
   Keywords : Physics and Astronomy;

   Abstract : Terahertz radiation is a useful tool for inducing lower-energy excitations in matter, where it can be used to cause structural changes through direct interaction with the crystal lattice. Sub-picosecond optical pulses can be used to generate intense broadband terahertz pulses through optical rectification in nonlinear crystals, reaching peak electric fields of several MV/m and conversion efficiencies as high as a few percent. READ MORE

3. 7. The effect of disorder on the axial anomaly in a lattice model in 1 + 1 dimensions

   University essay from KTH/Fysik

   Author : Agnes Wattrang; [2023]
   Keywords : Axial anomaly; tight-binding model; semiclassical physics; correlated disorder.; Axial kiral anomali; tätbindningsmodell; semiklassisk fysik; korrelerad oordning;

   Abstract : This work investigates the effect of a disorder potential, that represents impurities/dislocations in the lattice, on the time-dependent signature of the axial anomaly in a one-band tight-binding model in one spatial dimension. The tight-binding model is solved numerically and the simulation results are compared with a semiclassical expression for the time-dependent axial density, n5(t), due to Nielsen and Ninomiya [1]. READ MORE

4. 8. Electron-skyrmion systems, in and out of equilibrium, and isolated or contacted to reservoirs

   University essay from Lunds universitet/Matematisk fysik; Lunds universitet/Fysiska institutionen

   Author : Emil Adam Jonatan Östberg; [2023]
   Keywords : skyrmion; skyrmions; NEGF; freen s function; quantum transport; non-equlibrium; topology; topological charge; skyrmionics; current induced; open system; Physics and Astronomy;

   Abstract : A Kondo lattice skyrmion model in contact with a macroscopic environment is simulated to explore skyrmion dynamics, which is an extension of previous work. The system is simulated using non-equilibrium Green's functions within the generalized Kadanoff-Baym ansatz and the wide band limit. READ MORE

5. 9. The cosmological polytope of the complete bipartite graph K_{2,n}

   University essay from KTH/Matematik (Avd.)

   Author : Erik Landin; [2023]
   Keywords : Polytopes; Cosmological polytopes; Gröbner bases; Graphs; Polytop; Kosmologiska polytop; Gröbner baser; Grafer;

   Abstract : A cosmological polytope of an undirected connected graph is a lattice polytope which when the graph is interpreted as a feynman diagram can be used to calculate the contribution of that feynman diagram to the wavefunction of some cosmological models. This contribution can be calculated using the canonical form of the cosmological polytope, which can be computed by taking the sum of the canonical forms of the facets of a subdivision of the cosmological polytope. READ MORE

6. 10. Phonons in 1-D Graphene Nanoribbons Probed with Raman Spectroscopy : Unraveling Fundamental Properties in 9-atom-wide Graphene Nanoribbons

   University essay from KTH/Skolan för elektroteknik och datavetenskap (EECS)

   Author : Angel Victor Labordet Alvarez; [2023]
   Keywords : 9-armchair graphene nanoribbons 9-AGNRs ; polarization Raman Spectroscopy PRS ; temperature-dependent Raman spectroscopy; thermal sensitivity; thermal stability; Grüneisen parameter χ ; anharmonicities; vibrational modes G; D; RBLM .; 9-armchair grafen nanoribbons 9-AGNRs ; polarisation Raman spektroskopi PRS ; temperaturberoende Raman spektroskopi; termisk känslighet; termisk stabilitet; Grüneisen parameter χ ; anharmoniciteter; vibrationslägen G; D; RBLM .;

   Abstract : This report employs advanced Raman spectroscopy techniques to investigate the fundamental properties of 9-AGNRs comprehensively. It is divided into two main sections addressing distinct aspects of 9-AGNR behavior. In the first section, Polarization Raman spectroscopy (PRS) probes phonon mode symmetries in 9-AGNRs. READ MORE