Speaker:
Dr. Dirk Sander
Institution:
Max Planck Institute of Microstructure Physics, Germany
Speaker Link:
Date:
Wednesday, October 24, 2018
Time:
4:00 pm
Location:
NS2 1201
Abstract:
Spin-polarized scanning tunneling microscopy at low temperature (8 K) and in high magnetic fields (6 T) is a powerful technique to investigate magnetic properties of individual nanoscale objects ranging in size form single atoms to several thousand atoms [1]. I focus on the magnetization reversal [2] and the spin-dependent electronic properties of bilayer Co [3], Fe-decorated Co and Fe islands on Cu(111). We find a novel noncollinear, helical magnetic order in the Fe islands, which is identified by a magnetic stripe contrast with a period of 1.28 nm [4,5] in bilayer islands. The periodicity increases to 2.2 nm in three-layer thick Fe islands [6]. The high spatial resolution of the spin-polarized scanning tunneling spectroscopy in combination with theory reveals the significance of structural and electronic relaxation [7] for the magnetic anisotropy, for subtle balances between ferromagnetic and antiferromagnetic exchange interaction, and for spin-dependent transport properties [8] of individual, single nanostructures.
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Spin-polarized scanning tunneling microscopy at low temperature (8 K) and in high magnetic fields (6 T) is a powerful technique to investigate magnetic properties of individual nanoscale objects ranging in size form single atoms to several thousand atoms [1]. I focus on the magnetization reversal [2] and the spin-dependent electronic properties of bilayer Co [3], Fe-decorated Co and Fe islands on Cu(111). We find a novel noncollinear, helical magnetic order in the Fe islands, which is identified by a magnetic stripe contrast with a period of 1.28 nm [4,5] in bilayer islands. The periodicity increases to 2.2 nm in three-layer thick Fe islands [6]. The high spatial resolution of the spin-polarized scanning tunneling spectroscopy in combination with theory reveals the significance of structural and electronic relaxation [7] for the magnetic anisotropy, for subtle balances between ferromagnetic and antiferromagnetic exchange interaction, and for spin-dependent transport properties [8] of individual, single nanostructures.
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[1] H. Oka, O. Brovko, M. Corbetta, V. Stepanyuk, D. Sander, J. Kirschner
Rev. Mod. Phys. 86 (2014), 1127.
Rev. Mod. Phys. 86 (2014), 1127.
[2] S. Ouazi, G. Rodary, S. Wedekind, H. Oka, D. Sander, J. Kirschner
Phys. Rev. Lett. 108 (2012) 107206.
[3] H. Oka, P. Ignatiev, S. Wedekind, G. Rodary, L. Niebergall, V. Stepanyuk, D. Sander, J. Kirschner
Science 327 (2010) 843.
[4] S. Phark, J. Fischer, M. Corbetta, D. Sander, K. Nakamura, J. Kirschner
Nat. Commun. 5 (2014) 5183.
Nat. Commun. 5 (2014) 5183.
[5] J. Fischer, L. Sandtratskii, S. Phark, S. Ouazi, A. Pasa, D. Sander, St. Parkin
Nat. Commun. 7 (2016) 13000.
[6] J. Fischer, L. Sandratskii, S. Phark, D. Sander, St. Parkin
Phys. Rev. B 96 (2017) 140407(R).
[7] O. Brovko, D. Bazhanov, H. Meyerheim, D. Sander, V. Stepanyuk, J. Kirschner
Surface Science Reports 69 (2014) 159.
[8] H. Oka, K. Tao, S. Wedekind, G. Rodary, V. Stepanyuk, D. Sander, J. Kirschner
Phys. Rev. Lett. 107 (2011) 187201.
Host:
John Hemminger
Wilson Ho