Elektromehanička nestabilnost u nanoelektromehaničkim sustavima

master's thesis

• Title (english): Electromechanical instability in nanoelectromechanical systems
• Author: Larisa Gomaz
• Mentor: Danko Radić (mentor)
• Committee member: Danko Radić (predsjednik povjerenstva)
• Committee member: Krešimir Kumerički (član povjerenstva)
• Committee member: Nikola Poljak (član povjerenstva)
• Committee member: Matko Milin (član povjerenstva)
• Committee member: Željko Skoko (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2018-09-20, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract

U ovom radu analiziran je DC - elektronski transport kroz vodljivu karbonsku nanocjevčicu u vanjskom magnetskom polju koja je učvršćena između nemagnetskog i magnetskog mikrokontakta na koje je doveden prednapon. Karbonska nanocjevčica promatrana je kao kvantna točka unutar režima kulonske blokade u kojoj su elektronska stanja Zeemanski rascijepljena i dovoljno razmaknuta obzirom na termalnu ”razmazanost” Fermijeve plohe pa je svako Zeemanski rascijepljeno stanje ponaosob smatrano odgovornim za elektronski transport. Magnetomotorno vezanje izmedu električne struje kroz karbonsku nanocjevčicu i njenih mehaničkih vibracija može rezultirati elektromehaničkom nestabilnošću i samoekscitiranim oscilacijama. S obzirom na to, u ovom radu dan je klasični teorijski opis elektromehaničke nestabilnosti u navedenom nanoelektromehaničkom sustavu u području dozvoljenih fizikalnih parametara pri čemu je elektromehanička nestabilnost određena nastankom samoekscitiranih oscilacija mehaničkih i električnih obzervabli koje uočavamo kao gubitak stabilnosti stacionarne fiksne točke i nastanak graničnog kola u faznom prostoru oscilatora.

Abstract (english)

In this thesis we analyze DC - electronic transport through a carbon nanotube suspended between normal - metal source and spin - polarized drain in external magnetic field symmetrically biased. The carbon nanotube is considered as a quantum dot within Coulomb blockade regime in which electronic states are Zeeman - split and distant enough with respect to the thermal smearing of the Fermi surface so that each of the Zeeman - split states is responsible for electronic transport. Magnetomotive coupling between electric current through the carbon nanotube and its mechanical vibrations may lead to an electromechanical instability and self - excited mechanical vibrations. This thesis contains a classical theoretical description of electromechanical instability in the nanoelectromechanical system in the field of allowed physical parameters. Electromechanical instability is determined by occurrence of the self - excited mechanical vibrations that we notice as loss of stability of stationary fixed point and occurrence of a limit cycle in a phase space of an oscillator.

• Keywords: nanoelektromehanički sustav; karbonska nanocjevčica; elektromehanička nestabilnost; samoekscitirane oscilacije
• Keywords (english): nanoelectromechanical system; carbon nanotube; electromechanical instability; self - excited vibrations
• Language: croatian
• URN:NBN: urn:nbn:hr:217:872155
• Study programme: Title: Physics and Computer Science; specializations in: Education; Course: Education; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: magistar/magistra fizike i informatike (magistar/magistra fizike i informatike)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2018-11-20 14:14:24