The atomic-scale spin structure of individual isolated Skyrmions in an ultrathin film is investig... more The atomic-scale spin structure of individual isolated Skyrmions in an ultrathin film is investigated in real space by spin-polarized scanning tunneling microscopy. Their axial symmetry as well as their unique rotational sense is revealed by using both out-of-plane and in-plane sensitive tips. The size and shape of Skyrmions change as a function of the magnetic field. An analytical expression for the description of Skyrmions is proposed and applied to connect the experimental data to the original theoretical model describing chiral Skyrmions. Thereby, the relevant material parameters responsible for Skyrmion formation can be obtained.
Growth, electronic properties, and magnetic properties of an Fe monolayer (ML) on an Ir/YSZ/Si(11... more Growth, electronic properties, and magnetic properties of an Fe monolayer (ML) on an Ir/YSZ/Si(111) multilayer system have been studied using spin-polarized scanning tunneling microscopy. Our experiments reveal a magnetic nano-skyrmion lattice, which is fully equivalent to the magnetic ground state that has previously been observed for the Fe ML on Ir(111) bulk single crystals. In addition, the experiments indicate that the interface-stabilized skyrmion lattice is robust against local atomic lattice distortions induced by multilayer preparation.
Load-dependent studies of the frictional properties of the carbon compounds graphite, diamond, am... more Load-dependent studies of the frictional properties of the carbon compounds graphite, diamond, amorphous carbon, and C 60 were performed by friction force spectroscopy in air and dry argon. During the experiments, the surface was profiled at low loads without wear or ...
We have studied the nanomechanical properties of thin 0957-4484/7/4/007/img1 films epitaxially gr... more We have studied the nanomechanical properties of thin 0957-4484/7/4/007/img1 films epitaxially grown on GeS(001) substrates by scanning force methods. The local frictional coefficient derived for 0957-4484/7/4/007/img1 islands was found to be significantly smaller than on the GeS(001) substrate demonstrating that well ordered 0957-4484/7/4/007/img1 films can lower the frictional force even compared with a layered material. In the second part of
Spin-resolved scanning tunneling microscopy is used to reveal a commensurate hexagonal nanoskyrmi... more Spin-resolved scanning tunneling microscopy is used to reveal a commensurate hexagonal nanoskyrmion lattice in the hcp stacked Fe monolayer on Ir(111). The exact nature of the spin configuration is due to magnetic interactions between the Fe atoms and the Ir substrate, either originating from polarization effects, or due to a 3-site hopping mechanism of the Dzyaloshinsky-Moriya interaction leading to a canting of the Dzyaloshinsky-Moriya vector with respect to the interface.
We demonstrate that magnetic exchange force spectroscopy allows for a quantitative determination ... more We demonstrate that magnetic exchange force spectroscopy allows for a quantitative determination of the distance-dependent magnetic exchange interaction across a vacuum gap. Experiments were performed on the antiferromagnetic Fe monolayer on W(001) with magnetically sensitive tips and compared to first-principles calculations performed for different cluster tip models. For stable tips, which can be distinguished from unstable tips by analyzing the dissipation signal, very good agreement with theory is observed.
The spin textures of ultra-thin magnetic layers exhibit surprising variety. The loss of inversion... more The spin textures of ultra-thin magnetic layers exhibit surprising variety. The loss of inversion symmetry at the interface of the magnetic layer and substrate gives rise to the so-called Dzyaloshinskii-Moriya interaction which favors non-collinear spin arrangements with unique rotational sense. Here we review the application of spin-polarized scanning tunneling microscopy to such systems, which has led to the discovery of interface-induced chiral domain walls and spin spirals. Recently, different interface-driven skyrmion lattices have been found, and the writing as well as the deleting of individual skyrmions based on local spin-polarized current injection has been demonstrated. These interface-induced non-collinear magnetic states offer new exciting possibilities to study fundamental magnetic interactions and to tailor material properties for spintronic applications.
ABSTRACT We have used scanning tunneling microscopy (STM) under ultrahigh vacuum conditions in or... more ABSTRACT We have used scanning tunneling microscopy (STM) under ultrahigh vacuum conditions in order to study the morphology and chemical structure of several icosahedral samples directly in real space with a lateral and vertical resolution on a subnanometer scale. For the interpretation of the STM images it was necessary also to perform scanning electron microscopy studies on the same samples. A hierarchy of structural units is found with pentagonal-shaped structures on a variety of length scales.
The atomic-scale spin structure of individual isolated Skyrmions in an ultrathin film is investig... more The atomic-scale spin structure of individual isolated Skyrmions in an ultrathin film is investigated in real space by spin-polarized scanning tunneling microscopy. Their axial symmetry as well as their unique rotational sense is revealed by using both out-of-plane and in-plane sensitive tips. The size and shape of Skyrmions change as a function of the magnetic field. An analytical expression for the description of Skyrmions is proposed and applied to connect the experimental data to the original theoretical model describing chiral Skyrmions. Thereby, the relevant material parameters responsible for Skyrmion formation can be obtained.
Growth, electronic properties, and magnetic properties of an Fe monolayer (ML) on an Ir/YSZ/Si(11... more Growth, electronic properties, and magnetic properties of an Fe monolayer (ML) on an Ir/YSZ/Si(111) multilayer system have been studied using spin-polarized scanning tunneling microscopy. Our experiments reveal a magnetic nano-skyrmion lattice, which is fully equivalent to the magnetic ground state that has previously been observed for the Fe ML on Ir(111) bulk single crystals. In addition, the experiments indicate that the interface-stabilized skyrmion lattice is robust against local atomic lattice distortions induced by multilayer preparation.
Load-dependent studies of the frictional properties of the carbon compounds graphite, diamond, am... more Load-dependent studies of the frictional properties of the carbon compounds graphite, diamond, amorphous carbon, and C 60 were performed by friction force spectroscopy in air and dry argon. During the experiments, the surface was profiled at low loads without wear or ...
We have studied the nanomechanical properties of thin 0957-4484/7/4/007/img1 films epitaxially gr... more We have studied the nanomechanical properties of thin 0957-4484/7/4/007/img1 films epitaxially grown on GeS(001) substrates by scanning force methods. The local frictional coefficient derived for 0957-4484/7/4/007/img1 islands was found to be significantly smaller than on the GeS(001) substrate demonstrating that well ordered 0957-4484/7/4/007/img1 films can lower the frictional force even compared with a layered material. In the second part of
Spin-resolved scanning tunneling microscopy is used to reveal a commensurate hexagonal nanoskyrmi... more Spin-resolved scanning tunneling microscopy is used to reveal a commensurate hexagonal nanoskyrmion lattice in the hcp stacked Fe monolayer on Ir(111). The exact nature of the spin configuration is due to magnetic interactions between the Fe atoms and the Ir substrate, either originating from polarization effects, or due to a 3-site hopping mechanism of the Dzyaloshinsky-Moriya interaction leading to a canting of the Dzyaloshinsky-Moriya vector with respect to the interface.
We demonstrate that magnetic exchange force spectroscopy allows for a quantitative determination ... more We demonstrate that magnetic exchange force spectroscopy allows for a quantitative determination of the distance-dependent magnetic exchange interaction across a vacuum gap. Experiments were performed on the antiferromagnetic Fe monolayer on W(001) with magnetically sensitive tips and compared to first-principles calculations performed for different cluster tip models. For stable tips, which can be distinguished from unstable tips by analyzing the dissipation signal, very good agreement with theory is observed.
The spin textures of ultra-thin magnetic layers exhibit surprising variety. The loss of inversion... more The spin textures of ultra-thin magnetic layers exhibit surprising variety. The loss of inversion symmetry at the interface of the magnetic layer and substrate gives rise to the so-called Dzyaloshinskii-Moriya interaction which favors non-collinear spin arrangements with unique rotational sense. Here we review the application of spin-polarized scanning tunneling microscopy to such systems, which has led to the discovery of interface-induced chiral domain walls and spin spirals. Recently, different interface-driven skyrmion lattices have been found, and the writing as well as the deleting of individual skyrmions based on local spin-polarized current injection has been demonstrated. These interface-induced non-collinear magnetic states offer new exciting possibilities to study fundamental magnetic interactions and to tailor material properties for spintronic applications.
ABSTRACT We have used scanning tunneling microscopy (STM) under ultrahigh vacuum conditions in or... more ABSTRACT We have used scanning tunneling microscopy (STM) under ultrahigh vacuum conditions in order to study the morphology and chemical structure of several icosahedral samples directly in real space with a lateral and vertical resolution on a subnanometer scale. For the interpretation of the STM images it was necessary also to perform scanning electron microscopy studies on the same samples. A hierarchy of structural units is found with pentagonal-shaped structures on a variety of length scales.
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