Blar i NTNU Open på forfatter "Qaiumzadeh, Alireza"

Viser treff 21-37 av 37

    • Quasiclassical theory for antiferromagnetic metals 

      Fyhn, Eirik Holm; Brataas, Arne; Qaiumzadeh, Alireza; Linder, Jacob Wüsthoff (Peer reviewed; Journal article, 2023)
      Unlike ferromagnetism, antiferromagnetism cannot readily be included in the quasiclassical Keldysh theory because of the rapid spatial variation in the directions of of the magnetic moments. The quasiclassical framework ...

    • Scattering theory of transport through disordered magnets 

      Jakobsen, Martin Fonnum; Qaiumzadeh, Alireza; Brataas, Arne (Journal article; Peer reviewed, 2019)
      We present a scattering theory of transport through noncollinear disordered magnetic insulators. For concreteness, we study and compare the random field model (RFM) and the random anisotropy model (RAM). The RFM and RAM ...

    • Second order coherence of squeezed magnons in a thermal environment 

      Rørbakken, Øyvind B. (Master thesis, 2023)
      Spinbølger, eller magnoner, er interessante å studere på grunn av deres potensial som informasjonsbærende signaler i kondensert materie uten ohmisk tap, i motsetning til elektroner. Fenomenet kvantestramming er også et ...

    • Spin and Thermal Hall Effects in the Strongly Correlated Kane-Mele-Hubbard Model 

      Fosstveit, Stein Kåre Lundeberg (Master thesis, 2022)
      Vi studerer egenskapene til en utvidet Kane-Mele-Hubbard-modell på honeycombgitteret når Dzyaloshinskii-Moriya-vekselvirkninger for nest nærmeste naboer er rettet ut av planet. Ved hjelp av middelfeltteorien for Schwingerbosoner ...

    • Spin dynamics in magnetic structures: A numerical study 

      Wirak, Mette (Master thesis, 2019)
      Spintronikk foreslår en alterativ måte å gjøre datalagring på, som vil kunne være både mer effektiv og raskere. Grunnlaget for forskningsfeltet er den kvantemekaniske egenskapen spinn, som gjennom spinnbølger kan forflyttes ...

    • Spin Superfluidity in Biaxial Antiferromagnetic Insulators 

      Qaiumzadeh, Alireza; Skarsvåg, Hans Langva; Holmqvist, Cecilia; Brataas, Arne (Journal article; Peer reviewed, 2017)
      Antiferromagnets may exhibit spin superfluidity since the dipole interaction is weak. We seek to establish that this phenomenon occurs in insulators such as NiO, which is a good spin conductor according to previous studies. ...

    • Spin-orbit-induced dynamics of magnetic textures 

      Kristiansen, Lars André (Master thesis, 2017)
      We investigate the effect of the relativistic spin-orbit interaction on the dynamics of both ferromagnetic and antiferromagnetic domain walls driven by spin waves. Initially, we derive the free energy and the equations of ...

    • Superconducting Proximity Effect and Long-Ranged Triplets in Dirty Metallic Antiferromagnets 

      Fyhn, Eirik Holm; Brataas, Arne; Qaiumzadeh, Alireza; Linder, Jacob Wüsthoff (Journal article; Peer reviewed, 2023)
      Antiferromagnets have no net spin splitting on the scale of the superconducting coherence length. Despite this, antiferromagnets have been observed to suppress superconductivity in a similar way as ferromagnets, a phenomenon ...

    • Theory of Antisymmetric Exchange in Metallic Antiferromagnetic Thin Films 

      Hanslin, Sander Øglænd (Master thesis, 2019)
      Den antisymmetriske Dzyaloshinskii-Moriya interaksjonen (DMI) er viktig for stabilisering av ikke-kollineære magnetiske faser. Ved å sammenligne uttrykket for mikromagnetisk fri energi med den feltteoretiske partisjonsfunksjonen, ...

    • Thermal squeezing and nonlinear spectral shift of magnons in antiferromagnetic insulators 

      Shiranzaei, Mahroo; Troncoso, Roberto; Fransson, Jonas; Brataas, Arne; Qaiumzadeh, Alireza (Peer reviewed; Journal article, 2022)
      We investigate the effect of magnon–magnon interactions on the dispersion and polarization of magnon modes in collinear antiferromagnetic (AF) insulators at finite temperatures. In two-sublattice AF systems with uniaxial ...

    • Thermoelectric Properties of (Anti)ferromagnet - Superconductor Hybrid Junctions 

      Naess, Kristian (Master thesis, 2019)
      Denne masteroppgaven undersøker de termiske egenskapene til både en ferromagnet-superleder overgang og en antiferromagnet-superleder overgang. Målet med oppgaven er å utlede, grafisk fremstille og evaluere termisk ledningsevne, ...

    • Topological Magnon-Phonon Hybrid Excitations and Hall Effects in Two-Dimensional Ferromagnets 

      Kløgetvedt, Jostein Negård (Master thesis, 2023)
      Mye forskning har hatt til hensikt å undersøke vekselvirkningene mellom magnoner og fononer, som utgjør fundamentale eksitasjoner i magnetisk ordnede materialer. Forskningsfunnene tyder på at disse vekselvirkningene kan ...

    • Topological Transport Properties of Non-Abelian Magnons in a Spiral Phase Ferromagnetic Insulator 

      Lind-Olsen, Jesper (Master thesis, 2023)
      I denne masteroppgaven studerer vi tverrgående topologiske transportegenskaper i en ferromagnetisk insulator med Dzyaloshinskii-Moriya vekselvirkninger i planet. Denne vekselvirkningen er en nøkkelkomponent i å indusere ...

    • Ultrafast control of spin interactions in honeycomb antiferromagnetic insulators 

      Losada, Juan Manuel; Brataas, Arne; Qaiumzadeh, Alireza (Journal article; Peer reviewed, 2019)
      Light enables the ultrafast, direct, and nonthermal control of the exchange and Dzyaloshinskii-Moriya interactions. We consider two-dimensional honeycomb lattices described by the Kane-Mele-Hubbard model at half filling ...

    • Ultrafast generation and dynamics of isolated skyrmions in antiferromagnetic insulators 

      Khoshlahni, Rohollah; Qaiumzadeh, Alireza; Bergman, Anders; Brataas, Arne (Peer reviewed; Journal article, 2019)
      Based on atomistic spin dynamics simulations, we report the ultrafast generation of single antiferromagnetic (AFM) skyrmions in a confined geometry. This process is achieved through an effective magnetic field induced by ...

    • Ultrafast manipulation of Heisenberg exchange and Dzyaloshinskii–Moriya interactions in antiferromagnetic insulators 

      Losada, Juan Manuel (Master thesis, 2019)
      Light enables ultrafast, direct and nonthermal control of the exchange and Dzyaloshinskii-Moriya interactions. We consider two-dimensional honeycomb lattices described by the Kane-Mele-Hubbard model at half filling and in ...

    • Ultrafast Two-Magnon Excitation in Two-Dimensional Antiferromagnetic Insulators 

      Haug, Trond Hjerpekjøn (Master thesis, 2020)
      Spinneksitasjoner i todimensjonale antiferromagnetiske materialer manifesteres som spinnbølger som også er kjent som magnoner. Magnoner er bosoniske kvasipartikler som kan eksiteres ved hjelp av en laserindusert forstyrrelse ...