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Ballistic conductance of suspended nanowires: An ab initio description

Ballistic conductance of suspended nanowires: An ab initio description. M. Czerner 1 , A. Bagrets 1 , N. Papanikolaou 2 , V.S. Stepanyuk 3 and I. Mertig 1 1 Martin-Luther-Universit ät Halle, Germany

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Ballistic conductance of suspended nanowires: An ab initio description

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  1. Ballistic conductance of suspended nanowires: An ab initio description M. Czerner1, A. Bagrets1, N. Papanikolaou2, V.S. Stepanyuk3 and I. Mertig1 1Martin-Luther-Universität Halle, Germany 2Institute of Material Science, National Center for Scientific Research „Demokritos“, Athens, Greece 3 Max-Planck-Institute Mikrostrukturphysik Halle, Germany

  2. Content • Motivation • Method • Parity oscillations • Relaxation and conductance • Impurity scattering • Ballistic magnetoconductance • Summary

  3. Motivation Metallic Nanowires Conductance H. Ohnishi, Yu. Kondo, K. Takayanagi,Nature 395, 780 (1998)

  4. KKR Green‘s function method Semi-infinite leads Suspended nanowire

  5. Landauer theory with Green‘s functions Landauer formula 1 Sample 2 Conductance Matrix elements H.U. Baranger and A.D. Stone, Phys. Rev. B 40, 8169 (1989)

  6. Cu fcc [100] Conductance of Cu wires Local partial DOS at central Cu atom Conductance histogram at T=4.2K for Cu, A. I. Yanson, PhD. Thesis, Leiden University, the Netherlands, 2001. G = 1.10 G0

  7. Conductance of Cu wires Local partial DOS at central Cu atom Conductance histogram at T=4.2K for Cu, A. I. Yanson, PhD. Thesis, Leiden University, the Netherlands, 2001. G = 2.59 G0 Cu fcc [100]

  8. Parity oscillation in the conductance of Cu wires Experiment KKR calculation R.H.M. Smit et al., Phys. Rev. Lett. 91, 076805-1 (2003) M. Czerner, diploma thesis, MLU Halle (2003)

  9. Even-odd parity effect in the density of states s-LDOS p-LDOS

  10. c b a Distance d (Å) Stress and conductance in a Cu wire Averaged stress Conductance Average stress per Cu atom (ev/ų) V.S.Stepanyuk et al., Phys. Rev. B (2003) M. Czerner, diploma thesis, MLU Halle (2003)

  11. sp impurity (Z = 11 ... 16) Conductance through sp-atoms

  12. sp impurity (Z = 11 ... 16) Conductance through sp-atoms

  13. sp impurity (Z = 11 ... 16) Conductance through sp-atoms

  14. 3d impurity (Z = 21 ... 30) Conductance through 3d transition metal atoms

  15. 3d impurity (Z = 21 ... 30) Conductance through 3d transition metal atoms

  16. 3d impurity (Z = 21 ... 30) Conductance through 3d transition metal atoms

  17. 3d impurity (Z = 21 ... 30) Conductance through 3d transition metal atoms

  18. Conductance through 3d transition metal atoms

  19. Conductance through 3d transition metal atoms

  20. Conductance through 3d transition metal atoms

  21. Conductance of Co wires DOS Conductance

  22. Ballistic Magnetoconductance Parallel configuration (P) Antiparallel configuration (AP) MR =(gP – gAP)/gAP x 100%

  23. Ballistic Magnetoconductance of Co wires MR = 38 % MR = 29 %

  24. Summary • Conductance depends strongly on geometry • of the junction • II. Parity oscillations • III. Relaxation enhances conductance • III. Impurity scattering modulates conductance • IV. Ballistic magnetoconductance is ~50 %

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