Novel Approaches for Exploring Electron Interactions in Reduced Dimensions
Abstract
Summary:
Arguably, some of the most intriguing phenomena in contemporary condensed matter research can be observed in systems of “reduced” dimensions. In cases where electrons are not allowed to propagate freely in all three spatial directions, a newfound interplay with other electrons and other collective excitations can often be observed. The confinement of the electrons can thus lead to altered electronic properties or, in extreme cases, completely different phase behavior. For instance, the results can range from electronic states with massless Dirac fermions to potent pairing mechanisms for unconventional superconductivity. Ultimately, the implications of said “confinement” would depend on the material the electrons propagate in and the other degrees of freedom it enables and inhabits.
This thesis is concerned with forming and studying such systems of “reduced” dimensions and the physical phenomena they exhibit. The work is based on six research papers covering various topics, materials, and experimental techniques. Three papers examine the physical structure of state-of-the-art quantum materials and pathways to modify and control their behavior and quality. The remaining three focus on electron interactions with collective modes of excitation, both in van der Waals materials and in ferromagnetic and antiferromagnetic structures and heterostructures.
Sammendrag:
Flere underlige og fascinerende fysiske fenomener i moderne materialfysikk forekommer i systemer med «redusert» dimensjonalitet: altså en- eller to-dimensjonale materialer. I situasjoner der elektronene ikke står fritt til å bevege seg i alle tre romlige retninger, vil nettopp denne begrensingen av elektronenes «frihet» kunne føre til nye interaksjoner – enten innbyrdes mellom elektronene selv, eller med andre frihetsgrader i systemet. Resultatene kan variere fra mindre eller moderate endringer materialets elektroniske egenskaper. For eksempel, at de strømledende elektronene som blir tyngre eller tilnærmet «masseløse», eller mer drastiske endringer, som faseovergang til «superledning» med netto null elektrisk motstand.
Denne avhandlingen bygger på seks forskningsartikler som alle omhandler materialsystemer i «reduserte» dimensjoner, og de fysiske fenomenene som opptrer i disse. Tre av arbeidene omhandler todimensjonale kvantematerialer, og setter søkelys på hvordan å utforme eller manipulere disse for å optimalisere materialkvaliteten, eller skreddersy strømledningsoppførselen deres. De siste tre arbeidene omhandler samvirkningen mellom elektroner og andre, delokaliserte energieksitasjoner, som gittervibrasjoner («fononer») og/eller magnetiske spinbølger («magnoner»).
Has parts
Paper 1: Røst, Håkon Ivarssønn; Chellappan, Rajesh Kumar; Strand, Frode Sneve; Grubišić-Čabo, Antonija; Reed, Benjamen P.; Prieto, Mauricio J.; Tǎnase, Liviu C.; Caldas, Lucas de Souza; Wongpinij, Thipusa; Euaruksakul, Chanan; Schmidt, Thomas; Tadich, Anton; Cowie, Bruce; Li, Zheshen; Cooil, Simon; Wells, Justin. Low-Temperature Growth of Graphene on a Semiconductor. Journal of Physical Chemistry C 2021 ;Volum 125.(7) s. 4243-4252 https://dx.doi.org/10.1021/acs.jpcc.0c10870 This article is Open Access (CC BY 3.0)Paper 2: Røst, Håkon Ivarssønn; Reed, Benjamen P.; Strand, Frode Sneve; Durk, Joseph A.; Evans, D. Andrew; Grubišić-Čabo, Antonija; Wan, Gary; Cattelan, Mattia; Prieto, Mauricio J.; Gottlob, Daniel M.; Tǎnase, Liviu C.; De Souza Caldas, Lucas; Schmidt, Thomas; Tadich, Anton; Cowie, Bruce C. C.; Chellappan, Rajesh Kumar; Wells, Justin William; Cooil, Simon P.. A Simplified Method for Patterning Graphene on Dielectric Layers. ACS Applied Materials & Interfaces 2021 ;Volum 13.(31) s. 37510-37516 https://doi.org/10.1021/acsami.1c09987 This article is Open Access (CC BY 3.0)
Paper 3: Røst, Håkon Ivarssønn; Cooil, Simon; Åsland, Anna Cecilie; Ali, Ayaz; Belle D. Branson; Hu, Jinbang; Sadowski, Jerzy T.; Mazzola, Federico; Wells, Justin W. Phonon-Induced Mass Enhancements in a Wide Bandgap Material
Paper 4: Røst, Håkon Ivarssønn; Tosi, Ezequil; Strand, Frode S.; Åsland, Anna Cecilie; Lacovig, Paolo; Lizzit, Silvano; Wells, Justin W. Probing the Atomic Arrangement of Sub-Surface Dopants in a Silicon Quantum Device Platform
Paper 5: Røst, Håkon Ivarssønn; Mazzola, Federico; Bakkelund, Johannes; Åsland, Anna Cecilie; Hu, Jinbang; Cooil, Simon P.; Polly, Craig M.; Wells, Justin W. Disentangling Electron-Boson Interactions on the Surface of a Familiar Ferromagnet
Paper 6: Mæland, Kristian; Røst, Håkon Ivarssønn; Wells, Justin William; Sudbø, Asle. Electron-magnon coupling and quasiparticle lifetimes on the surface of a topological insulator. Physical review B (PRB) 2021 ;Volum 104.(12) https://doi.org/10.1103/PhysRevB.104.125125
Paper 7: Michels, Leander; Richter, Annika; Chellappan, Rajesh Kumar; Røst, Håkon Ivarssønn; Behsen, Alenka Djarmila; Wells, Kristin Høydalsvik; Leal, Luciano; Santana, Vilany; Blawid, Rosana; da Silva, Geraldo J.; Cooil, Simon; Wells, Justin William; Blawid, Stefan. Electronic and structural properties of the natural dyes curcumin, bixin and indigo. RSC Advances 2021 ;Volum 11.(23) s. 14169-14177 https://doi.org/10.1039/D0RA08474C This article is Open Access (CC BY 3.0)
Paper 8: Åsland, Anna Cecilie; Bakkelund, Johannes; Thingstad, Even; Røst, Håkon Ivarssønn; Cooil, Simon P.; Hu, Jinbang; Vobornik, Ivana; Fuji, Jun; Sudbø, Asle; Wells, Justin W.; Mazzola, Federico. One-Dimensional Spin-Polarised Surface States - A Comparison of Bi(112) with Other Vicinal Bismuth Surfaces
Paper 9: Mamedov, Damir; Åsland, Anna Cecilie; Cooil, Simon P.; Bakkelund, Johannes; Wells, Justin W.; Karazhanov, Smagul. Enhanced Hydrophobicity of CeO2 Thin Films by Surface Engineering