http://sites.google.com/site/quevedin/Jaime Ferrer   Diego Carrascal      Víctor García Suárez
Huge Magnetic Anisotropy in Nanostructures   1/07/2011                                                         4
Two magnetic statesMagnetism: TM ions                                      Ultimate Bit:                       MAE: 5d ato...
Magnetic in Bulk PhaseNonmagnetic inbulk, magnetic at nanoscale        “THEORETICAL ENGINEERING”                       Tot...
EMAE                                         t/τ                               EMAE / KT                               M =...
EMAE      Volume    EMAE = Edipolar + ESpin-Orbit                                                           Edipolar >> ES...
5d                 4d  3d                         5sHuge Magnetic Anisotropy in Nanostructures   1/07/2011                ...
S,L                                                            S,L                          d                             ...
Phys. Rev. Lett. 99, 183401 (2007)                                    Phys. Rev. Lett. 101, 069903(E) (2008)              ...
Phys. Rev. B 75, 075415 (2007)Huge Magnetic Anisotropy in Nanostructures   1/07/2011                                      ...
 See if reducing the number of TM atoms we  can understand things better And try organic matrices:        Oscillating sp...
Spin ½ molecules                             C                                               H                NMetallocene...
Cobalt                           Copper                           Gold   UNCONVENTIONAL MAGNETISM IN AuCp2         Huge Ma...
Huge Magnetic Anisotropy in Nanostructures   1/07/2011                                                         19
Cobalt                             Copper                           Gold    UNCONVENTIONAL MAGNETISM IN AuPc         Phys....
Huge Magnetic Anisotropy in Nanostructures   1/07/2011                                                         21
 Look  for molecules containing 5d elements →  large SO interaction Unconventional magnetism in gold organometallic mole...
SIESTA   The Siesta method; developments and applicability.   E. Artacho, E. Anglada, et al. J. Phys.: Condens. Matter 20...
Huge Magnetic Anisotropy in Nanostructures   1/07/2011                                                         25
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Transcript of "Ismanam 2011 fernandez seivane"

  1. 1. http://sites.google.com/site/quevedin/Jaime Ferrer Diego Carrascal Víctor García Suárez
  2. 2. Huge Magnetic Anisotropy in Nanostructures 1/07/2011 4
  3. 3. Two magnetic statesMagnetism: TM ions Ultimate Bit: MAE: 5d atoms Our rationale Stability: organic chemistry Huge Magnetic Anisotropy in Nanostructures 1/07/2011 5
  4. 4. Magnetic in Bulk PhaseNonmagnetic inbulk, magnetic at nanoscale “THEORETICAL ENGINEERING” Total Spin ~ 1-10 • Push up other multiplets to high energies • Increase magnetic anisotropy Huge Magnetic Anisotropy in Nanostructures 1/07/2011 6
  5. 5. EMAE t/τ EMAE / KT M = M 0e τ = 10 7 e sec Time requirements for a τ = 1012 seconds bit EMAE,Critical = EBlocking 50 KTB Blocking Temperature Set T B = 300 K E Blocking = 1300 meVTo give a flavor: Record: TB in a Mollecular Magnet = 3K ;Record TB in an inorganic nanostructure: 1.5 K in Co dimers Huge Magnetic Anisotropy in Nanostructures 1/07/2011 8
  6. 6. EMAE Volume EMAE = Edipolar + ESpin-Orbit Edipolar >> ESpin-Orbit in bulk EMAE Edipolar Edipolar << ESpin-Orbit in nanoEBlocking . ESpin-Orbit Critical ~ 25 nm for Fe particles 10 nm for Co particles Critical Volume V Huge Magnetic Anisotropy in Nanostructures 1/07/2011 9
  7. 7. 5d 4d 3d 5sHuge Magnetic Anisotropy in Nanostructures 1/07/2011 10
  8. 8. S,L S,L d 1 E E|| EMAE 2 Huge Magnetic Anisotropy in Nanostructures 1/07/2011 11
  9. 9. Phys. Rev. Lett. 99, 183401 (2007) Phys. Rev. Lett. 101, 069903(E) (2008) Pt2: ground state parallel to the axis, Anisotropy of ~ 100 meV, S=1 Ir2: ground state parallel to the axis, Anisotropy of ~ 60 meV, S=2, some changes in the spin with the distance Pd2: ground state perpendicular to the axis, tiny Anisotropy ~ 5 meV, S=1, sudden jump in L a bit above the equilibrium distance Au2: ground state in singlet, L=0, S=0. Many of this, or very similar results, have been confirmed indepently and by different methods by other groups, for instance Piotr Błoński and Jürgen Hafner 2011 J. Phys.: Condens. Matter 23, 136001 or Ruijuan Xiao, Daniel Fritsch et al., Phys Rev. B 82, 205125Huge Magnetic Anisotropy in Nanostructures 1/07/2011 13
  10. 10. Phys. Rev. B 75, 075415 (2007)Huge Magnetic Anisotropy in Nanostructures 1/07/2011 15
  11. 11.  See if reducing the number of TM atoms we can understand things better And try organic matrices: Oscillating spin-density pattern in gold metallocenephthalocyanines and metallocenes and phthalocyanine molecules Diego Carrascal, Lucas Fernández-Seivane, Jaime Ferrer Phys. Rev. B, 80, 18, 184415 (2009); arXiv:0904.1138v1 Huge Magnetic Anisotropy in Nanostructures 1/07/2011 16
  12. 12. Spin ½ molecules C H NMetallocenes (TMCp2) Phthalocyanines (TMPc) Huge Magnetic Anisotropy in Nanostructures 1/07/2011 17
  13. 13. Cobalt Copper Gold UNCONVENTIONAL MAGNETISM IN AuCp2 Huge Magnetic Anisotropy in Nanostructures 1/07/2011 18
  14. 14. Huge Magnetic Anisotropy in Nanostructures 1/07/2011 19
  15. 15. Cobalt Copper Gold UNCONVENTIONAL MAGNETISM IN AuPc Phys. Rev. B, 80, 18, 184415 (2009) arXiv:0904.1138v1 Huge Magnetic Anisotropy in Nanostructures 1/07/2011 20
  16. 16. Huge Magnetic Anisotropy in Nanostructures 1/07/2011 21
  17. 17.  Look for molecules containing 5d elements → large SO interaction Unconventional magnetism in gold organometallic molecules Most molecules have S=0 or ½ A few Alkene-based molecules had a higher spin and MAE ~ 10 meV Failure to find huge magnetic anisotropies Huge Magnetic Anisotropy in Nanostructures 1/07/2011 23
  18. 18. SIESTA The Siesta method; developments and applicability. E. Artacho, E. Anglada, et al. J. Phys.: Condens. Matter 20, 064208 (2008).SIESTA+SO On-site approximation for spin-orbit coupling in LCAO density functional methods. L. Fernandez-Seivane, M. A. Oliveira, S. Sanvito, J. Ferrer, J. Phys. : Condens. Matter 18 7999 (2006); arxiv:cond-mat/0601093 Predictions for the formation of new atomic chains in Mechanically Controllable Break Junction experiments L. Fernandez-Seivane, V. M. Garcia-Suarez, J. Ferrer Phys. Rev. B 75, 075415 (2007); arXiv:cond mat/0611624v1 Magnetic anisotropies of late transition metal atomic clusters Lucas Fernández-Seivane, Jaime Ferrer Phys. Rev. Lett. 99, 183401 (2007); arXiv:cond-mat/0610879v2 Oscillating spin-density pattern in gold metallocene and phthalocyanine molecules Diego Carrascal, Lucas Fernández-Seivane, Jaime Ferrer Phys. Rev. B, 80, 18, 184415 (2009); arXiv:0904.1138v1 Magnetic properties of small Pt-capped Fe, Co, and Ni clusters: A density functional theory study Sahoo, S.; Hucht, A.; Gruner, M. E.; et al. Phys. Rev. B 82, 054418 (2010); arxviv:0907.2678 Magnetic properties of Fe-2n and (FePt)(n) (n <= 5) clusters and magnetic anisotropy of transition metal dimers Boufala, K.; Fernandez-Seivane, L.; Ferrer, J.; et al. Journal of Magnetism and Magnetic Materials, 322, 21 Pages:3428-3437 (2010) Huge Magnetic Anisotropy in Nanostructures 1/07/2011 24
  19. 19. Huge Magnetic Anisotropy in Nanostructures 1/07/2011 25

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