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Mats Persson (1) , Hyo-June Lee (2) , and Wilson Ho (2)

Exchange splitting in electronic states of single atoms and magnetic coupling in single dimers and trimers on a surface. Mats Persson (1) , Hyo-June Lee (2) , and Wilson Ho (2) ( 1) Dept. of Applied Physics, Chalmers/Göteborg University, SWEDEN

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Mats Persson (1) , Hyo-June Lee (2) , and Wilson Ho (2)

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  1. Exchange splitting in electronic states of single atoms and magnetic coupling in single dimers and trimers on a surface Mats Persson(1), Hyo-June Lee(2), and Wilson Ho(2) (1)Dept. of Applied Physics, Chalmers/Göteborg University, SWEDEN (2)Dept. of Physics and Astronomy and Dept. of Chemistry , University of California, Irvine, USA

  2. Outline Tunneling spectra with a non-magnetic tip and density functional calculations of: • Non-magnetic Au atom and dimer on NiAl(110) surface • Magnetic Co, Fe, Mn atoms and dimers, and Fe trimer on NiAl(110) surface ______________________________________________________________________ N. Nilius, T. M. Wallis, M. Persson, and W. Ho., Phys. Rev. Lett. 90, 196103 (2003) H. J. Lee, W. Ho, and M. Persson, Phys. Rev. Lett. 92, 186802 (2004)

  3. Non-magnetic Au atom and dimers on a NiAl(110) surface • STS of Au adatom and ad-dimers. • Density functional calculation (PAW-GGA) VASP

  4. Au Adatom and Ad-dimers* * Nilius, Wallis, Persson, and Ho, Phys. Rev. Lett. 90, 196103 (2003)

  5. Tunneling Spectra and Images of an Au Ad-dimer

  6. Density Functional Calculations: Au Adatom and Ad-dimers PW-PAW-GGA (VASP) Ad-dimer Adatom

  7. Au Adatom

  8. Au Ad-dimer

  9. Resonance Energy Splittings of Dimers

  10. Magnetic atoms, dimers and trimer on a NiAl(110) surface* • STS of Co, Fe, and Mn adatoms and ad-dimers and Fe ad-trimer • Density functional calculation (PAW-GGA) VASP ___________________________________________________________ *H. J. Lee, W. Ho, and M. Persson, Phys. Rev. Lett. 92, 186802 (2004)

  11. Magnetic adatoms at 17 K

  12. Calculated Magnetic Adatom DOS

  13. Two Level System with a Spin Non-magnetic Ferromagnetic Anti Ferromagnetic

  14. Magnetic Co and Fe Addimers: LDOS Fe2/NiAl(110) Co2/NiAl(110) E0(AFM)-E0(FM) = 0.42eV E0(AFM)-E0(FM) = 0.45eV m = 3.5mB m = 5.9mB Strong adatom-adatom interaction Interadatom distance (d = 2.2 Å) shorter than bridge-bridge distance (2.9 Å)

  15. Magnetic Mn Addimer: LDOS E0(AFM)-E0(FM) = 0.036eV m = 8.9mB Weak adatom-adatom interaction Interadatom distance (d = 3.0 Å) close to the bridge-bridge distance (2.9 Å)

  16. Magnetic Fe Ad-trimer m = 9.5mB

  17. Concluding Remarks • Unoccupied Kohn-Sham states give a useful approximation and physical insights of tunneling spectra of resonances in atom nanostructures on NiAl(110) • Non-Kondo resonance signatures of the spin state in magnetic adatoms, ad-dimers and ad-trimer

  18. Acknowledgements Experiments: Niklas Nilius and Mitch Wallis, UC Irvine, USA Theory: Doug Mills and Ruqian Wu, UC Irvine, USA R. Bechara Muniz, Univ. Federal Fluminense, Niteroi, Brazil Funding:

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