exchange splitting in electronic states of single atoms and magnetic coupling in single dimers and...
TRANSCRIPT
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
Outline
• Non-magnetic Au atom and dimer on NiAl(110) surface
• Magnetic Co, Fe, Mn atoms and dimers, and Fe trimer on NiAl(110) surface
Tunneling spectra with a non-magnetic tip and density functional calculations of:
______________________________________________________________________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)
Non-magnetic Au atom and dimers on a NiAl(110) surface
• STS of Au adatom and ad-dimers.• Density functional calculation (PAW-GGA)
VASP
Au Adatom and Ad-dimers*
* Nilius, Wallis, Persson, and Ho, Phys. Rev. Lett. 90, 196103 (2003)
Tunneling Spectra and Images of an Au Ad-dimer
Density Functional Calculations: Au Adatom and Ad-dimers
PW-PAW-GGA (VASP)
Adatom Ad-dimer
Au Adatom
Au Ad-dimer
Resonance Energy Splittings of Dimers
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)
Magnetic adatoms at 17 K
Calculated Magnetic Adatom DOS
Two Level System with a Spin
Ferromagnetic Anti FerromagneticNon-magnetic
Magnetic Co and Fe Addimers: LDOS
Co2/NiAl(110)
E0(AFM)-E0(FM) = 0.42eV
Strong adatom-adatom interaction Interadatom distance (d = 2.2 Å) shorter than bridge-bridge distance (2.9 Å)
Fe2/NiAl(110)
E0(AFM)-E0(FM) = 0.45eV
Magnetic Mn Addimer: LDOS
E0(AFM)-E0(FM) = 0.036eV
Weak adatom-adatom interaction Interadatom distance (d = 3.0 Å) close to the bridge-bridge distance (2.9 Å)
Magnetic Fe Ad-trimer
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
AcknowledgementsExperiments: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: