Blar i NTNU Open på forfatter "Marthinsen, Astrid"
-
A first-principles Study of epitaxial Interfaces between Graphene and GaAs
Marthinsen, Astrid (Master thesis, 2014)Epitaxial interfaces between graphene and GaAs(111) have been investigated through a first-principles study using density functional theory (DFT). The GaAs(111) surface at the interface is assumed to be 2x2 reconstructed ... -
Coupling and competition between ferroelectricity, magnetism, strain, and oxygen vacancies in AMnO3 perovskites
Marthinsen, Astrid; Faber, Carina; Aschauer, Ulrich; Spaldin, Nicola A.; Selbach, Sverre Magnus (Journal article; Peer reviewed, 2016)We use first-principles calculations based on density functional theory to investigate the interplay between oxygen vacancies, A-site cation size/tolerance factor, epitaxial strain, ferroelectricity, and magnetism in the ... -
First principles study of epitaxial strain induced phenomena and chemical expansion in perovskite oxides
Marthinsen, Astrid (Doctoral theses at NTNU;2018:285, Doctoral thesis, 2018)The many exotic properties found in complex oxides have great potential for device applications. Complex oxides within the perovskite structure are particularly attractive, as they display a large diversity of chemical ... -
First-Principles Calculations of Oxygen Vacancy Formation in Epitaxially Strained La1-xCaxMnO3
Thøgersen, Rasmus Vester (Master thesis, 2016)Using epitaxial strain as a degree of freedom is a promising way to tailor the properties in thin films of transition metal oxides. Since the ground state of such materials tend to have many competing low-energy states ... -
First-principles study of the effect of (111) strain on octahedral rotations and structural phases of LaAlO3
Moreau, Magnus; Marthinsen, Astrid; Selbach, Sverre Magnus; Tybell, Per Thomas Martin (Journal article; Peer reviewed, 2017)The structural and electronic response of LaAlO3 to biaxial strain in the (111) plane is studied by density functional theory (DFT) and compared with strain in the (001) plane and isostatic strain. For (111) strain, in-plane ... -
Goldstone-like phonon modes in a (111)-strained perovskite
Marthinsen, Astrid; Griffin, Sinead M; Moreau, Magnus; Grande, Tor; Tybell, Per Thomas Martin; Selbach, Sverre Magnus (Journal article; Peer reviewed, 2018)Goldstone modes are massless particles resulting from spontaneous symmetry breaking. Although such modes are found in elementary particle physics as well as in condensed-matter systems like superfluid helium, superconductors, ... -
Microscopic Link between Electron Localization and Chemical Expansion in AMnO3 and ATiO3 Perovskites (A = Ca, Sr, Ba)
Marthinsen, Astrid; Grande, Tor; Selbach, Sverre Magnus (Peer reviewed; Journal article, 2020)The microscopic origin of chemical expansion in perovskite oxides, due to formation of oxygen vacancies accompanied by formal reduction of a 3d transition metal, is studied by first-principles calculations. We compare the ... -
Strain-phonon coupling in (111)-oriented perovskite oxides
Moreau, Magnus; Marthinsen, Astrid; Selbach, Sverre Magnus; Tybell, Per Thomas Martin (Journal article; Peer reviewed, 2017)Strain-phonon coupling, in terms of the shift in phonon frequencies under biaxial strain, is studied by density functional theory calculations for 20 perovskite oxides strained in their (111) and (001) planes. While the ...