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Испољавање сопствених и индукованих магнетских својстава графенских наноструктура.

dc.contributor.advisorTadić, Milan
dc.contributor.otherPeeters, François M.
dc.contributor.otherRaković, Dejan
dc.contributor.otherPartoens, Bart
dc.contributor.otherArsoski, Vlada
dc.creatorGrujić, Marko M.
dc.date.accessioned2016-07-10T17:08:21Z
dc.date.available2016-07-10T17:08:21Z
dc.date.available2020-07-03T08:33:38Z
dc.date.issued2015-05-26
dc.identifier.urihttp://eteze.bg.ac.rs/application/showtheses?thesesId=3125
dc.identifier.urihttp://nardus.mpn.gov.rs/handle/123456789/5690
dc.identifier.urihttps://fedorabg.bg.ac.rs/fedora/get/o:11427/bdef:Content/download
dc.identifier.urihttp://vbs.rs/scripts/cobiss?command=DISPLAY&base=70036&RID=47594511
dc.description.abstractThe dissertation can be roughly divided into two parts. In the first part it deals with magnetic properties of quasi-zero dimensional graphene structures, such as nanodots and nanorings. In particular, a circular graphene quantum dot is analyzed in Chapter 3 using the Dirac-Weyl equation. The energy and the optical absorption spectra are computed for the case of the present external magnetic field. The results are obtained for two distinct boundary conditions, namely infinite-mass and zigzag boundary conditions, which model different physics in the structure with different edges. It is found that the energy spectrum of a dot with zigzag boundary condition exhibits a zero energy band regardless of the value of the magnetic field, while for the infinite mass boundary condition the zero energy states appear only for high magnetic fields in the form of the zeroth Landau level. The analytical results are compared to those obtained from the tight-binding model in order to show the validity range of the continuum model. It is found that the continuum model with infinite mass boundary condition describes rather well its tight binding counterpart, which can partially be attributed to blurring of the mixed edges by the staggered potential. The mean-field Hubbard model is subsequently used to investigate the formation of the antiferromagnetic phase in hexagonal graphene quantum rings with inner zigzag edges. The outer edge of the ring is taken to be either zigzag or armchair, and it is found that both types of structures exhibit a larger antiferromagnetic interaction than hexagonal quantum dots. This difference could be partially ascribed to the larger number of zigzag edges per unit area in rings than in dots. Furthermore, edge states localized on the inner ring edge are found to hybridize differently than the edge states of dots, which results in important differences in the magnetism of graphene rings and dots. The largest staggered magnetization is found when the outer edge has a zigzag shape. However, narrow rings with armchair outer edge are found to have larger staggered magnetization than zigzag hexagons. The edge defects are shown to have the least effect on magnetization when the outer ring edge is armchair shaped.sr
dc.description.abstractOva doktorska disertacija se može grubo podeliti u dva dela. U prvom delu, ona se bavi magnetskim svojstvima kvazi-nulto dimenzionih grafen- skih struktura, kao što su nanotačke i nanoprstenovi. Konkretno, kružna grafenska kvantna tačka je analizirana u poglav u 3 koristeći Dirak-Vejlovu jednačinu. Energetska stanja i optički apsorpcioni spektar su izračunati za slučaj primenjenog spoljašnjeg magnetnog polja. Rezultati su dobijeni za dva različita slučaja, primenom graničnog uslova beskonačne mase i takoz- vanog cikcak graničnog uslova, koji opisuju strukture sa različitim vrstama ivica. Pronađeno je da energetski spektar tačke za cikcak granični uslov podržava nultoenergetski nivo, bez obzira na vrednost magnetskog polja, dok se za granični uslov beskonačane mase nultoenergetska stanja pojavljuju samo za visoke vrednosti magnetskog polja i to u obliku nultog Landauovog nivoa. Analitički dobijeni rezultati su zatim upoređeni sa rezultatima dobijenim pomoću metoda jake veze, da bi se odredila oblast važenja kontinualnog mod- ela. Pronađeno je da se kontinualni model sa graničnim uslovom beskonačne mase dobro slaže sa metodom jake veze, što se donekle može pripisati mini- mizovanju uticaja ivica, što je posledica naizmeničnog potencijala. Nakon ovoga disertacija se bavi analizom formiranja antiferomagnetizma u heksagonalnim grafenskim kvantnim prstenovima sa cikcak unutrašnjom ivicom koristeći Habardov model u aproksimaciji srednjeg polja. Spoljna ivica prstena je ili cikcak ili foteljastog tipa. Pronađeno je da obe vrste struktura pokazuju veću sklonost ka antiferomagnetizmu nego heksagonalne kvantne tačke. Ova razlika se delimično može pripisati većoj dužini cik- cak ivica u prstenovima nego u tačkama. Pored toga, hibridizacija ivič- nih stanja lokalizovanih na unutrašnjoj strani prstena je drugačije prirode nego hibridizacija stanja na ivici tačaka, što dovodi do bitnih razlika mag- netizma prstenova u odnosu na tačke. Najveća magnetizacija je dobijena za slučaj kada je i spoljašnja ivica cikcak tipa. Ipak, vrlo uski prstenovi sa...en
dc.formatapplication/pdf
dc.languageen
dc.publisherУниверзитет у Београду, Електротехнички факултетsr
dc.relationinfo:eu-repo/grantAgreement/MESTD/Integrated and Interdisciplinary Research (IIR or III)/45003/RS//
dc.rightsopenAccessen
dc.sourceУниверзитет у Београдуsr
dc.subjectgraphenesr
dc.subjectgrafenen
dc.subjectmagnetic eldsr
dc.subjectmagnetic momentsr
dc.subjectquantum dotsr
dc.subjectspinorbit couplingsr
dc.subjectvalleysr
dc.subjecttransportsr
dc.subjectmagnetsko poljeen
dc.subjectmagnetni momenaten
dc.subjectkvantna tačkaen
dc.subjectspin-orbitna interakcijaen
dc.subjectdolinaen
dc.subjecttransporten
dc.titleManifestations of intrinsic and induced magnetic properties of graphene nanostructuressr
dc.titleИспољавање сопствених и индукованих магнетских својстава графенских наноструктура.en
dc.typedoctoralThesis
dc.rights.licenseBY-NC
dcterms.abstractТадић, Милан; Пеетерс, Франçоис М.; Раковић, Дејан; Партоенс, Барт; Aрсоски, Влада; Грујић, Марко М.; Манифестатионс оф интринсиц анд индуцед магнетиц пропертиес оф грапхене наноструцтурес; Манифестатионс оф интринсиц анд индуцед магнетиц пропертиес оф грапхене наноструцтурес; Ispoljavanje sopstvenih i indukovanih magnetskih svojstava grafenskih nanostruktura.;
dc.identifier.fulltexthttp://nardus.mpn.gov.rs/bitstream/id/5116/Grujic_Marko.pdf
dc.identifier.fulltexthttp://nardus.mpn.gov.rs/bitstream/id/5115/Disertacija3665.pdf


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