Browsing NTNU Open by Author "Sudbø, Asle"
Now showing items 1-20 of 43
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Analytic Study of Ultracold, Synthetically Spin–Orbit Coupled, Weakly Interacting, Two-Component Bose Gases Residing on Bravais Lattices
Janssønn, Andreas Tiedemann Glaser (Master thesis, 2018)In this Master's thesis, the behavior of ultracold, synthetically spin orbit coupled, weakly interacting, two-component Bose gases residing on Bravais lattices, is explored analytically. In particular, utilizing a mean ... -
Anomalous domain wall velocity and Walker breakdown in hybrid systems with anisotropic exchange
Enoksen, Henrik; Sudbø, Asle; Linder, Jacob (Journal article; Peer reviewed, 2013)It has recently been proposed that spin-transfer torques in magnetic systems with anisotropic exchange can be strongly enhanced, reducing the characteristic current density with up to four orders of magnitude compared to ... -
Antiferromagnetic magnons as highly squeezed Fock states underlying quantum correlations
Kamra, Akashdeep; Thingstad, Even; Rastelli, Gianluca; Duine, Rembert A.; Brataas, Arne; Belzig, Wolfgang; Sudbø, Asle (Peer reviewed; Journal article, 2019)Employing the concept of two-mode squeezed states from quantum optics, we demonstrate a revealing physical picture for the antiferromagnetic ground state and excitations. Superimposed on a Néel ordered configuration, a ... -
Chiral Phonon Transport Induced by Topological Magnons
Thingstad, Even; Kamra, Akashdeep; Brataas, Arne; Sudbø, Asle (Peer reviewed; Journal article, 2019)The plethora of recent discoveries in the field of topological electronic insulators has inspired a search for boson systems with similar properties. There are predictions that ferromagnets on a two-dimensional honeycomb ... -
Conformality loss and quantum criticality in topological Higgs electrodynamics in 2+1 dimensions
Nogueira, Flavio S.; van den Brink, Jeroen; Sudbø, Asle (Journal article; Peer reviewed, 2019)The electromagnetic response of topological insulators and superconductors is governed by a modified set of Maxwell equations that derive from a topological Chern-Simons (CS) term in the effective Lagrangian with coupling ... -
Criticality and novel quantum liquid phases in Ginzburg--Landau theories with compact and non-compact gauge fields
Smiseth, Jo (Doktoravhandlinger ved NTNU, 1503-8181; 2005:144, Doctoral thesis, 2005)We have studied the critical properties of three-dimensional U(1)-symmetric lattice gauge theories. The models apply to various physical systems such as insulating phases of strongly correlated electron systems as well as ... -
Current Control of Magnetism in Two-Dimensional Fe3GeTe2
Johansen, Øyvind; Risinggård, Vetle Kjær; Sudbø, Asle; Linder, Jacob; Brataas, Arne (Journal article; Peer reviewed, 2019)The recent discovery of magnetism in two-dimensional van der Waals systems opens the door to discovering exciting physics. We investigate how a current can control the ferromagnetic properties of such materials. Using ... -
Drag and Phases in Interacting and Spin-Orbit Coupled Superfluid Bose-Einstein Condensates
Hartman, Stian Thomas Heimdal (Master thesis, 2018)Motivated by previous work on drag effects in superfluid Bose-Einstein condensates, the Bose-Hubbard model on the square lattice is considered using mean-field theory, and a method for computing the superfluid drag density ... -
Electric and magnetic signatures of boundary states in topological insulators and superconductors
Rex, Stefan (Doctoral theses at NTNU;2017:271, Doctoral thesis, 2017)This thesis is based on original research that was carried out in the field of topological phases in quantum condensed matter physics. The results have been published in five papers in Physical Review B, which form the ... -
Electron-phonon coupling in graphene
Hole-Drabløs, Kristian Framhus (Master thesis, 2018)The aim of this Master thesis was to perform a theoretical study of the electron-phonon coupling in graphene. The main results of the thesis are the electron-phonon coupling constant as a function of ... -
Enhancement of superconductivity mediated by antiferromagnetic squeezed magnons
Erlandsen, Eirik; Kamra, Akashdeep; Brataas, Arne; Sudbø, Asle (Journal article; Peer reviewed, 2019)We theoretically investigate magnon-mediated superconductivity in a heterostructure consisting of a normal metal and a two-sublattice antiferromagnetic insulator. The attractive electron-electron pairing interaction is ... -
Interplay between superconductivity and ferromagnetism on a topological insulator
Linder, Jacob; Tanaka, Yukio; Yokoyama, Takehito; Sudbø, Asle; Nagaosa, Naoto (Journal article; Peer reviewed, 2010)We study theoretically proximity-induced superconductivity and ferromagnetism on the surface of a topological insulator. In particular, we investigate how the Andreev-bound states are influenced by the interplay between ... -
Inverse proximity effect in s-wave and d-wave superconductors coupled to topological insulators
Hugdal, Henning Goa; Amundsen, Morten; Linder, Jacob; Sudbø, Asle (Journal article; Peer reviewed, 2019)We study the inverse proximity effect in a bilayer consisting of a thin s- or d-wave superconductor (S) and a topological insulator (TI). Integrating out the topological fermions of the TI, we find that spin-orbit coupling ... -
Investigating the excitation spectrum of a spin-orbit coupled Bose-Einstein condensate
Solli, Sigve (Master thesis, 2017)The excitation spectrum of a spin-orbit coupled Bose-Einstein condensate is investigated by the use of the Bose-Hubbard model and a mean-field approach. The undiagonalized Hamiltonian matrix for a general inversion-symmetric ... -
Josephson effect in S/F/S junctions: Spin bandwidth asymmetry versus Stoner exchange
Annunziata, Gaetano; Enoksen, Henrik; Linder, Jacob; Cuoco, Mario; Noce, Canio; Sudbø, Asle (Journal article; Peer reviewed, 2011)We analyze the dc Josephson effect in a ballistic superconductor/ferromagnet/superconductor junction by means of the Bogoliubov–de Gennes equations in the quasiclassical Andreev approximation. We consider the possibility ... -
Local versus Equal Load Sharing in the Fiber Bundle Model
Kjellstadli, Jonas Tøgersen (Doctoral theses at NTNU;2019:368, Doctoral thesis, 2019)Fracture is a huge field of research that includes physics, geology, materials science, and engineering. Most approaches are very specialized, but what if we instead want to focus on the big picture to look for general ... -
Magnon-mediated superconductivity on the surface of a topological insulator
Erlandsen, Eirik; Brataas, Arne; Sudbø, Asle (Journal article; Peer reviewed, 2020)We study superconductivity on the surface of a topological insulator, mediated by magnetic fluctuations in an adjacent ferromagnetic or antiferromagnetic insulator. Superconductivity can arise from effective interactions ... -
Majorana fermions manifested as interface states in semiconductor hybrid structures
Linder, Jacob; Sudbø, Asle (Journal article; Peer reviewed, 2010)Motivated by recent proposals for the generation of Majorana fermions in semiconducting hybrid structures, we examine possible experimental fingerprints of such excitations. Whereas previous works mainly have focused on ... -
Manipulating superconductivity in magnetic nanostructures in and out of equilibrium
Ouassou, Jabir Ali (Doctoral theses at NTNU;2019:57, Doctoral thesis, 2019)We consider nanostructures that are constructed from superconducting, ferromagnetic, and spin–orbit-coupled materials. These structures are analyzed both theoretically and numerically, under both equilibrium and nonequilibrium ... -
Maximum Entropy and Maximum Entropy Production in Macroecology
Sognnæs, Ida Andrea Braathen (Master thesis, 2011)The Maximum Entropy Theory of Ecology (METE), developed by John Harte, presents an entirely new method of making inferences in ecology. The method is based on the established mathematical procedure of Maximum Information ...