STM contrast inversion of the Fe(110) surface

Mándi, Gábor; Palotás, Krisztián

doi:10.1016/j.apsusc.2014.02.143

Cited by 13 publications

(24 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Instead, the spatial dependence of the local atomic spin quantization axes of the noncollinear magnetic surface is allowed. For simplicity, we omit the orbital dependence [58,60] of the electronic structure taken into account in Ref. 55, and the low bias limit is employed.…”

Section: A 3d-wkb Theory Of Combined Electron Charge and Spin Tunnelingmentioning

confidence: 99%

Theory of high-resolution tunneling spin transport on a magnetic skyrmion

2018

Self Cite

View full text Add to dashboard Cite

Tunneling spin transport characteristics of a magnetic skyrmion are described theoretically in magnetic scanning tunneling microscopy (STM). The spin-polarized charge current in STM (SP-STM) and tunneling spin transport vector quantities, the longitudinal spin current and the spin transfer torque, are calculated in high spatial resolution within the same theoretical framework. A connection between the conventional charge current SP-STM image contrasts and the magnitudes of the spin transport vectors is demonstrated that enables the estimation of tunneling spin transport properties based on experimentally measured SP-STM images. A considerable tunability of the spin transport vectors by the involved spin polarizations is also highlighted. These possibilities and the combined theory of tunneling charge and vector spin transport pave the way for gaining deep insight into electric-current-induced tunneling spin transport properties in SP-STM and to the related dynamics of complex magnetic textures at surfaces.

show abstract

Section: A 3d-wkb Theory Of Combined Electron Charge and Spin Tunnelingmentioning

confidence: 99%

Theory of high-resolution tunneling spin transport on a magnetic skyrmion

2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…Recently, the 3D-WKB method was successfully applied in a number of theoretical [15][16][17][18][19] and combined experimental-theoretical investigations [20].…”

Section: Methodsmentioning

confidence: 99%

What is the orientation of the tip in a scanning tunneling microscope?

Mándi

Teobaldi

Palotás

2015

Progress in Surface Science

Self Cite

View full text Add to dashboard Cite

We introduce a statistical correlation analysis method to obtain information on the local geometry and orientation of the tip used in scanning tunneling microscopy (STM) experiments based on large scale simulations. The key quantity is the relative brightness correlation of constant-current topographs between experimental and simulated data. This correlation can be analyzed statistically for a large number of modeled tip orientations and geometries. Assuming a stable tip during the STM scans and based on the correlation distribution, it is possible to determine the tip orientations that are most likely present in an STM experiment, and exclude other orientations. This is especially important for substrates such as highly oriented pyrolytic graphite (HOPG) since its STM contrast is strongly tip dependent, which makes interpretation and comparison of STM images very challenging. We illustrate the applicability of our method considering the HOPG surface in combination with tungsten tip models of two different apex geometries and 18144 different orientations. We calculate constant-current profiles along the $<1\bar{1}00>$ direction of the HOPG(0001) surface in the $|V|\le 1$ V bias voltage range, and compare them with experimental data. We find that a blunt tip model provides better correlation with the experiment for a wider range of tip orientations and bias voltages than a sharp tip model. Such a combination of experiments and large scale simulations opens up the way for obtaining more detailed information on the structure of the tip apex and more reliable interpretation of STM data in the view of local tip geometry effects.Comment: Progress in Surface Science, accepted for publication, 25 pages manuscript, 9 figures, abstract shortene

show abstract

“…The main advantage of using the density matrix formalism is that electronic and spin struc- within the same theoretical framework [24]. The charge (Ĩ) and vector spin (T) transport of the electron tunneling transition between the ath sample surface atom and the tip apex atom at energy E can be represented by the following traces in spin space: Since e S · e T = cos(φ) with φ the angle between the spin quantization axes of the sample surface and the tip, the formula of the charge transport (conductance) is formally consistent with the spin-polarized Tersoff-Hamann model [35], except the fact that it explicitly includes the electronic structure of the tip apex [24,31]:…”

Section: Port In Stmmentioning

confidence: 99%

“…More details of the Fe(001) tip model can be found in Ref. [31]. The orbital-decomposed electronic structure data projected to the tip apex atom, n T τ (E) and m T τ (E), have been calculated using a 13 × 13 × 3 Monkhorst-Pack k-point grid.…”

Section: Computational Detailsmentioning

confidence: 99%

Enhancement of the spin transfer torque efficiency in magnetic STM junctions

Palotás¹,

Mándi²,

Szunyogh³

2016

Phys. Rev. B

Self Cite

View full text Add to dashboard Cite

We introduce a method for a combined calculation of charge and vector spin transport of elastically tunneling electrons in magnetic scanning tunneling microscopy (STM). The method is based on the three-dimensional Wentzel-Kramers-Brillouin (3D-WKB) approach combined with electronic structure calculations using first principles density functional theory. As an application, we analyze the STM contrast inversion of the charge current above the Fe/W(110) surface depending on the bias voltage, tip-sample distance and relative magnetization orientation between the sample and an iron tip. For the spin transfer torque (STT) vector we find that its in-plane component is generally larger than the out-of-plane component, and we identify a longitudinal spin current component, which, however, does not contribute to the torque. Our results suggest that the torquecurrent relationship in magnetic STM junctions follows the power law rather than a linear function.Consequently, we show that the ratio between the STT and the spin-polarized charge current is not constant, and more importantly, it can be tuned by the bias voltage, tip-sample distance and magnetization rotation. We find that the STT efficiency can be enhanced by about a factor of seven by selecting a proper bias voltage. Thus, we demonstrate the possible enhancement of the STT efficiency in magnetic STM junctions, which can be exploited in technological applications. We discuss our results in view of the indirect measurement of the STT above the Fe/W(110) surface reported by Krause et al. in Phys. Rev. Lett. 107, 186601 (2011).

show abstract

STM contrast inversion of the Fe(110) surface

Cited by 13 publications

References 35 publications

Theory of high-resolution tunneling spin transport on a magnetic skyrmion

Theory of high-resolution tunneling spin transport on a magnetic skyrmion

What is the orientation of the tip in a scanning tunneling microscope?

Enhancement of the spin transfer torque efficiency in magnetic STM junctions

Contact Info

Product

Resources

About