Browsing NTNU Open by Author "Sudbø, Asle"
Now showing items 1-20 of 60
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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 ... -
Collective effects in low-dimensional systems with coupled quasiparticles
Thingstad, Even (Doctoral theses at NTNU;2021:279, Doctoral thesis, 2021)Many of the most fascinating and challenging phenomena in condensed matter physics occur in systems with coupling between quasiparticles of different nature. This thesis is concerned with the study of collective effects ... -
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 ... -
Diagrammatic Monte Carlo based on irreducible vertices for the Hubbard model in the strong-coupling limit
Brekke, Bjørnulf (Master thesis, 2020)Vi presenterer en introduksjon til nye diagrammatiske metoder i sterk-kobling regimet, utviklet av Carlström [1]. Metoden er brukt spesifikt på den to-dimensjonale Hubbardmodellen. Den nyttes som et forsøk på å redusere ... -
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-magnon coupling and quasiparticle lifetimes on the surface of a topological insulator
Mæland, Kristian; Røst, Håkon Ivarssønn; Wells, Justin William; Sudbø, Asle (Peer reviewed; Journal article, 2021)The fermionic self-energy on the surface of a topological insulator proximity coupled to ferro- and antiferromagnetic insulators is studied. An enhanced electron-magnon coupling is achieved by allowing the electrons on 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 ... -
Elements of the Microscopic Origins of Time-Reversal Symmetry Breaking in Phase-Frustrated Multiband Superconductors
Johnsen Svingen, Christian (Master thesis, 2021)En rekke teoretiske og eksperimentelle studier har blitt publisert som følge av oppdagelsen av superledning i materialene ved navn jernpniktider. Med disse oppdagelsene som motivasjon og et mål om å utvide den teoretiske ... -
Eliashberg study of superconductivity induced by interfacial coupling to antiferromagnets
Thingstad, Even; Erlandsen, Eirik; Sudbø, Asle (Peer reviewed; Journal article, 2021)We perform Eliashberg calculations for magnon-mediated superconductivity in a normal metal, where the electron-magnon interaction arises from interfacial coupling to antiferromagnetic insulators. In agreement with previous ... -
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 ... -
Excitation Spectrum and Superfluidity of Weakly Interacting, Spin-Orbit Coupled Bose-Einstein Condensate
Mæland, Kristian (Master thesis, 2020)En svakt vekselvirkende, spinn-bane koblet, to-komponent, ultrakald Bose-gass bundet til et Bravais gitter blir studert. En analytisk framgangsmåte for å beskrive slike systemer i superfluid regimet blir presentert, motivert ... -
Fingerprints of Universal Spin-Stiffness Jump in Two-Dimensional Ferromagnets
Troncoso, Roberto; Brataas, Arne; Sudbø, Asle (Peer reviewed; Journal article, 2020)Motivated by recent progress on synthesizing two-dimensional magnetic van der Waals systems, we propose a setup for detecting the topological Berezinskii-Kosterlitz-Thouless phase transition in spintransport experiments ... -
First-order superconducting phase transition in a chiral p+ip system
Haugen, Håvard Homleid; Krohg, Fredrik Nicolai; Babaev, Egor; Sudbø, Asle (Peer reviewed; Journal article, 2021)We use large-scale Monte Carlo computations to study the phase transitions between a two-component chiral p -wave superconductor and normal state in zero external magnetic field. We find a first-order phase transition from ... -
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 ...