• About
  • Policies
  • What is openaccess
  • Library
  • Contact
Advanced search
      View Item 
      •   BUIR Home
      • University Library
      • Bilkent Theses
      • Theses - Department of Physics
      • Dept. of Physics - Master's degree
      • View Item
      •   BUIR Home
      • University Library
      • Bilkent Theses
      • Theses - Department of Physics
      • Dept. of Physics - Master's degree
      • View Item
      JavaScript is disabled for your browser. Some features of this site may not work without it.

      Magnetism of transition metal nanowires

      Thumbnail
      View / Download
      2.5 Mb
      Author
      Ataca, Can
      Advisor
      Çıracı, Salim
      Date
      2008
      Publisher
      Bilkent University
      Language
      English
      Type
      Thesis
      Item Usage Stats
      100
      views
      23
      downloads
      Abstract
      In this thesis we investigated structural, electronic and magnetic properties of 3d (light) transition metal (TM) atomic chains and Cr nanowires using firstprinciples pseudopotential plane wave calculations. Infinite periodic linear, dimerized linear and planar zigzag chain structures, as well as their short segments consisting of finite number of atoms and chromium nanowires have been considered. For most of the infinite periodic chains, neither linear nor dimerized linear structures are favored; to lower their energy the chains undergo a structural transformation to form planar zigzag and dimerized zigzag geometries. Dimerization in both infinite and finite chains are much stronger than the usual Peierls distortion and appear to depend on the number of 3d-electrons. As a result of dimerization, a significant energy lowering occurs which, in turn, influences the stability and physical properties. Metallic linear chain of vanadium becomes half-metallic upon dimerization. Infinite linear chain of scandium also becomes half-metallic upon transformation to the zigzag structure. The end effects influence the geometry, energetics and the magnetic ground state of the finite chains. Structure optimization performed using noncollinear approximation indicates significant differences from the collinear approximation. Variation of the cohesive energy of infinite and finite-size chains with respect to the number of 3d-electrons are found to mimic the bulk behavior pointed out by Friedel. Furthermore, we considered Cr nanowires, which have cross section comprising a few (4,5 - 9,12) atoms. Chromium nanowires are found to be in a local minimum in the Born-Oppenheimer surface and are ferrimagnetic metals. The type of coupling, as for ferromagnetic or antiferromagnetic, between neighboring Cr atoms depends on their interatomic distances. The spin-orbit coupling of finite chains are found to be negligibly small for finite molecules and Cr nanowires.
      Keywords
      ab initio
      transition metal molecules
      nanowires
      monatomic chains
      transition metal
      density functional theory
      first principles
      Permalink
      http://hdl.handle.net/11693/14724
      Collections
      • Dept. of Physics - Master's degree 160
      Show full item record

      Browse

      All of BUIRCommunities & CollectionsTitlesAuthorsAdvisorsBy Issue DateKeywordsTypeDepartmentsThis CollectionTitlesAuthorsAdvisorsBy Issue DateKeywordsTypeDepartments

      My Account

      Login

      Statistics

      View Usage StatisticsView Google Analytics Statistics

      Bilkent University

      If you have trouble accessing this page and need to request an alternate format, contact the site administrator. Phone: (312) 290 1771
      Copyright © Bilkent University - Library IT

      Contact Us | Send Feedback | Off-Campus Access | Admin | Privacy