Browsing NTNU Open by Author "Brekke, Bjørnulf"

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    • 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 ...

    • Interfacial magnon-mediated superconductivity in twisted bilayer graphene 

      Brekke, Bjørnulf; Sudbø, Asle; Brataas, Arne (Journal article; Peer reviewed, 2024)
      The interfacial coupling between electrons and magnons in adjacent layers can mediate an attractive electron–electron interaction and induce superconductivity. We consider magic-angle twisted bilayer graphene sandwiched ...

    • Low-energy properties of electrons and holes in CuFeS2 

      Brekke, Bjørnulf; Malyshev, Roman; Svenum, Ingeborg-Helene; Selbach, Sverre Magnus; Tybell, Per Thomas Martin; Brüne, Christoph; Brataas, Arne (Peer reviewed; Journal article, 2022)
      The antiferromagnetic semiconductor CuFeS2 belongs to a magnetic symmetry class that is of interest for spintronics applications. In addition, its crystal lattice is compatible with Si, making it possible to integrate it ...

    • Many-body effects on superconductivity mediated by double-magnon processes in altermagnets 

      Mæland, Kristian; Brekke, Bjørnulf; Sudbø, Asle (Journal article; Peer reviewed, 2024)
      Altermagnets exhibit a large electron spin splitting which can be understood as a result of strong coupling between itinerant electrons and localized spins. We consider superconductivity due to electron-magnon scattering, ...

    • Two-dimensional altermagnets: Superconductivity in a minimal microscopic model 

      Brekke, Bjørnulf; Brataas, Arne; Sudbø, Asle (Peer reviewed; Journal article, 2023)
      We propose a minimal toy model for a two-dimensional altermagnet. The model unravels altermagnetic properties at a microscopic level. We find spin-split electron and nondegenerate magnon bands with a d -wave symmetry. We ...