scholarly journals Zero-field skyrmionic states and in-field edge-skyrmions induced by boundary tuning

2022 ◽  
Vol 5 (1) ◽  
Author(s):  
Jonas Spethmann ◽  
Elena Y. Vedmedenko ◽  
Roland Wiesendanger ◽  
André Kubetzka ◽  
Kirsten von Bergmann
Keyword(s):  
Spin Dynamics ◽  
Transverse Component ◽  
Scanning Tunneling ◽  
Zero Field ◽  
Tunneling Microscopy ◽  
Pinning Effect ◽  
Field Edge ◽  
Dynamics Simulations ◽  
Magnetic Skyrmions ◽  
Edge Spin

AbstractWhen magnetic skyrmions are moved via currents, they do not strictly travel along the path of the current, instead their motion also gains a transverse component. This so-called skyrmion Hall effect can be detrimental in potential skyrmion devices because it drives skyrmions towards the edge of their hosting material where they face potential annihilation. Here we experimentally modify a skyrmion model system—an atomic Pd/Fe bilayer on Ir(111)—by decorating the film edge with ferromagnetic Co/Fe patches. Employing spin-polarized scanning tunneling microscopy, we demonstrate that this ferromagnetic rim prevents skyrmion annihilation at the film edge and stabilizes skyrmions and target states in zero field. Furthermore, in an external magnetic field the Co/Fe rim can give rise to skyrmions pinned to the film edge. Spin dynamics simulations reveal how a combination of different attractive and repulsive skyrmion-edge interactions can induce such an edge-pinning effect for skyrmions.

scholarly journals Discovery and characterization of a new type of domain wall in a row-wise antiferromagnet

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jonas Spethmann ◽  
Martin Grünebohm ◽  
Roland Wiesendanger ◽  
Kirsten von Bergmann ◽  
André Kubetzka
Keyword(s):  
Domain Wall ◽  
Spin Structure ◽  
Domain Walls ◽  
Spin Dynamics ◽  
Magnetic Interactions ◽  
Theoretical Modelling ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
New Type ◽  
Dynamics Simulations

AbstractAntiferromagnets have recently moved into the focus of application-related research, with the perspective to use them in future spintronics devices. At the same time the experimental determination of the detailed spin texture remains challenging. Here we use spin-polarized scanning tunneling microscopy to investigate the spin structure of antiferromagnetic domain walls. Comparison with spin dynamics simulations allows the identification of a new type of domain wall, which is a superposition state of the adjacent domains. We determine the relevant magnetic interactions and derive analytical formulas. Our experiments show a pathway to control the number of domain walls by boundary effects, and demonstrate the possibility to change the position of domain walls by interaction with movable adsorbed atoms. The knowledge about the exact spin structure of the domain walls is crucial for an understanding and theoretical modelling of their properties regarding, for instance, dynamics, response in transport experiments, and manipulation.

Stm Studies at Electrochemically Controlled Interfaces

1994 ◽  
Vol 332 ◽  
Author(s):  
S.M. Lindsay ◽  
J. Pan ◽  
T.W. Jing
Keyword(s):  
Electron Tunneling ◽  
Point Contact ◽  
Localized States ◽  
Scanning Tunneling ◽  
Zero Field ◽  
Tunneling Microscopy ◽  
Dna Oligomers ◽  
Synthetic Dna ◽  
Quantum Point

ABSTRACTWe use electrochemical methods to control the adsorption of molecules onto an electrode for imaging in-situ by scanning tunneling microscopy. Measurements of the barrier for electron tunneling show that the mechanism of electron transfer differs from vacuum tunneling. Barriers depend upon the direction of electron tunneling, indicating the presence of permanently aligned dipoles in the tunnel gap. We attribute a sharp dip in the barrier near zero field to induced polarization. We propose a ‘tunneling’ process consisting of two parts: One is delocalization of quantum-coherent states in parts of the molecular adlayer that hybridize strongly (interaction ≥ kT) with Bloch states in the metal. This gives rise to a quantum-point-contact conductance, Gc ≤ 2e2/h at a height zo. The other part comes from the exponential decay of the tails of localized states, G = Gc exp{−2K(z − z0)}. Because measured decay lengths, (2K‘)−1, are small (≈ 1 Å), STM contrast is dominated by the contour along which G[z0 (x,y)] = Gc. Measured changes in z0 are used to calculate images which are in reasonable agreement with observations. We illustrate this with images of synthetic DNA oligomers.

Surface-mediated spin dynamics probed by optical-pump–probe scanning tunneling microscopy

2019 ◽  
Vol 21 (14) ◽  
pp. 7256-7260 ◽  
Author(s):  
Zi-Han Wang ◽  
Cheul-Hyun Yoon ◽  
Shoji Yoshida ◽  
Yusuke Arashida ◽  
Osamu Takeuchi ◽  
...  
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Materials Science ◽  
Spin Dynamics ◽  
Functional Materials ◽  
Surface Effects ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Optical Pump ◽  
Pump Probe

In current materials science and technologies, surface effects on carrier and spin dynamics in functional materials and devices are of great importance.

MODIFICATION OF NORMAL-STATE AND SUPERCONDUCTING PROPERTIES OF HIGH-Tc OXIDES VIA TREATMENT BY METAL-PHTHALOCYANINES

1994 ◽  
Vol 08 (05) ◽  
pp. 615-639 ◽  
Author(s):  
LEONID GRIGORYAN ◽  
KYUYA YAKUSHI ◽  
A. V. NARLIKAR ◽  
P. K. DUTTA ◽  
S. B. SAMANTHA
Keyword(s):  
Metal Ion ◽  
Scanning Tunneling ◽  
Zero Field ◽  
Central Metal ◽  
Tunneling Microscopy ◽  
Absorption Data ◽  
Metal Phthalocyanines ◽  
Oxide Powders ◽  
Lower Magnitude ◽  
New Compounds

Exposure of Bi- or Tl-based high-T c oxide powders to vapors of metal-phthalocyanines MPc (M is Zn or Ni) resulted in the formation of a family of new compounds with modified crystal lattice parameters, electronic structure, phonon spectrum and magnetic properties as compared to the starting materials. Based on the combined X ray diffraction, scanning tunneling microscopy, optical, FT–IR and microwave absorption data, a model of crystal structure is proposed where the key feature is intercalation of MPc molecules between the Bi-O (Tl-O) bilayers. Values of dc magnetization at 300 K varied over two orders of magnitude as a function of chemical composition and nature of the central metal ion in MPc. Measurements of temperature dependence of magnetization of the intercalated samples revealed a divergence at low temperatures between the zero-field and the field-cooled cycles, though of lower magnitude as compared to the starting high-T c oxides. The results of this study suggest that treatment by MPc offers a possibility of controllable variation of key properties of high-T c oxides.

Self-assembly of alkylcatechols on HOPG investigated by scanning tunneling microscopy and molecular dynamics simulations

CrystEngComm ◽  
2012 ◽  
Vol 14 (1) ◽  
pp. 264-271 ◽  
Author(s):  
Javier Saiz-Poseu ◽  
Isaac Alcón ◽  
Ramon Alibés ◽  
Félix Busqué ◽  
Jordi Faraudo ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Scanning Tunneling Microscopy ◽  
Molecular Dynamics Simulations ◽  
Self Assembly ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Dynamics Simulations

scholarly journals Peptide conformation and oligomerization characteristics of surface-mediated assemblies revealed by molecular dynamics simulations and scanning tunneling microscopy

RSC Advances ◽  
2019 ◽  
Vol 9 (70) ◽  
pp. 41345-41350 ◽  
Author(s):  
Yimin Zou ◽  
Bin Tu ◽  
Lanlan Yu ◽  
Yongfang Zheng ◽  
Yuchen Lin ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Scanning Tunneling Microscopy ◽  
Bound States ◽  
Peptide Conformation ◽  
Md Simulations ◽  
Scanning Tunneling ◽  
Model Structure ◽  
Tunneling Microscopy ◽  
Peptide Conformations ◽  
Dynamics Simulations

The characteristics of peptide conformations in both solution and surface-bound states, using poly-glycine as a model structure, are analyzed by using molecular dynamics (MD) simulations and scanning tunneling microscopy (STM).

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