Electronic transport through single polyalanine molecules

Slawig, Diana; Nguyen, Thi Ngoc Ha; Yochelis, Shira; Paltiel, Yossi; Tegenkamp, Christoph

doi:10.1103/physrevb.102.115425

Cited by 6 publications

(10 citation statements)

References 29 publications

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“…As pointed out in the calculations presented in Ref. 29 and supported by recent transport measurements, 16 the molecular orbital structure seems to be significantly affected by high electric fields.…”

Section: Stm Probing Of the Spin Polarization By Sequential Switching...supporting

confidence: 69%

“…For typical set-points (V b , I t ) used in our two terminal transport experiments the total resistance is of the order of R 0 ≈ 1 V /1 nA = 1 GΩ. The resistance of the metallic nanostructure is in the order of R Au/Co/Au = 10 Ω and for the PA molecules we have obtained from mechanically break junction experiments R P A ≈ 10 M Ω, 16 thus these two smaller contributions originating from the magnetic substrate and PA molecules are negligible. Moreover, bias voltage and tunneling current were kept constant during the switching cycles of the magnetization, hence the resistance R 0 across the entire junction remains constant.…”

Section: Stm Probing Of the Spin Polarization By Sequential Switching...mentioning

confidence: 80%

“…[12][13][14] In order to measure the spin-polarization in helical molecules dc transport experiments down to the scale of single molecules are mandatory. 1,15,16 Moreover, combinations of magnetic contacts with defined magnetization directions are required for quantification of the spin polarization. 15 So far, atomic force microscopy (AFM) was used to probe the structure for understanding structure-property relations on the microscopic scale.…”

Section: Introductionmentioning

confidence: 99%

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Cooperative effect of electrons spin polarization in a hybrid nanostructure of a magnetic thin film with adsorbed chiral molecules studied with non-spin-polarized scanning tunneling microscopy

Ha¹,

Rasabathina²,

Hellwig³

et al. 2022

Preprint

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Polyalanine molecules (PA) with an α-helix conformation gathered recently a lot of interest as the propagation of electrons through the chiral backbone structure comes along with spin polarization of the transmitted electrons. By means of scanning tunneling microscopy and spectroscopy at ambient conditions, PA molecules adsorbed on surfaces of epitaxial magnetic Al 2 O 3 /Pt/Au/Co/Au nanostructures with perpendicular anisotropy were studied. Thereby, a correlation between the PA molecules ordering at the surface with the electron tunneling across this hybrid system as a function of the substrate magnetization orientation as well as the coverage density and helicity of the was observed. The highest spin polarization values, P, were found for well-ordered self-assembled monolayers and with a defined chemical coupling of the molecules to the magnetic substrate surface, showing that the current induced spin selectivity is a cooperative effect. Thereby, P deduced from the electron transmission along unoccupied molecular orbitals of the helical molecules is larger as compared to values derived from the occupied molecular orbitals. Apparently, the larger orbital overlap is resulting in a higher electron mobility yielding a higher P value. By switching the magnetization direction of the Co-layer, it was demonstrated that the non-spin-polarized STM can be used to study chiral molecules with a sub-molecular resolution, to detect properties of buried magnetic layers and to detect the spin polarization of the molecules from the change of the magnetoresistance of such hybrid structures.

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Section: Stm Probing Of the Spin Polarization By Sequential Switching...supporting

confidence: 69%

Section: Stm Probing Of the Spin Polarization By Sequential Switching...mentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Cooperative effect of electrons spin polarization in a hybrid nanostructure of a magnetic thin film with adsorbed chiral molecules studied with non-spin-polarized scanning tunneling microscopy

Ha¹,

Rasabathina²,

Hellwig³

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

“…For typical set points (V b , I t ) used in our two terminal transport experiments the total resistance is on the order of R 0 ≈ 1 V/1 nA = 1 GΩ. The resistance of the metallic nanostructure is on the order of R Au/Co/Au = 10 Ω, and for the PA molecules we have obtained from mechanical break junction experiments R PA ≈ 10 MΩ; 16 thus, these two smaller contributions originating from the magnetic substrate and PA molecules are negligible. Moreover, the bias voltage and tunneling current were kept constant during the switching cycles of the magnetization; hence, the resistance R 0 across the entire junction remains constant.…”

Section: Stm Probing Of the Spin Polarization By Sequential Switching...mentioning

confidence: 99%

“…12−14 In order to measure the spin polarization in helical molecules, dc transport experiments down to the scale of single molecules are mandatory. 1,15,16 Moreover, combinations of magnetic contacts with defined magnetization directions are required for quantification of the spin polarization. 15 So far, atomic force microscopy (AFM) has been used to probe the structure for an understanding of the structure−property relations on a microscopic scale.…”

Section: Introductionmentioning

confidence: 99%

Cooperative Effect of Electron Spin Polarization in Chiral Molecules Studied with Non-Spin-Polarized Scanning Tunneling Microscopy

Nguyen

Rasabathina

Hellwig

et al. 2022

ACS Appl. Mater. Interfaces

Self Cite

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Polyalanine molecules (PA) with an α-helix conformation have recently attracted a great deal of interest, as the propagation of electrons through the chiral backbone structure comes along with spin polarization of the transmitted electrons. By means of scanning tunneling microscopy and spectroscopy under ambient conditions, PA molecules adsorbed on surfaces of epitaxial magnetic Al 2 O 3 / Pt/Au/Co/Au nanostructures with perpendicular anisotropy were studied. Thereby, a correlation between the PA molecules ordering at the surface with the electron tunneling across this hybrid system as a function of the substrate magnetization orientation as well as the coverage density and helicity of the PA molecules was observed. The highest spin polarization values, P, were found for well-ordered selfassembled monolayers and with a defined chemical coupling of the molecules to the magnetic substrate surface, showing that the current-induced spin selectivity is a cooperative effect. Thereby, P deduced from the electron transmission along unoccupied molecular orbitals of the chiral molecules is larger as compared to values derived from the occupied molecular orbitals. Apparently, the larger orbital overlap results in a higher electron mobility, yielding a higher P value. By switching the magnetization direction of the Co layer, it was demonstrated that the non-spin-polarized STM can be used to study chiral molecules with a submolecular resolution, to detect properties of buried magnetic layers and to detect the spin polarization of the molecules from the change in the magnetoresistance of such hybrid structures.

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Spin‐Selective Electron Transport Through Single Chiral Molecules

Safari,

Matthes,

Schneider

et al. 2023

Small

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The interplay between chirality and magnetism is a source of fascination among scientists for over a century. In recent years, chirality‐induced spin selectivity (CISS) has attracted renewed interest. It is observed that electron transport through layers of homochiral molecules leads to a significant spin polarization of several tens of percent. Despite the abundant experimental evidence gathered through mesoscopic transport measurements, the exact mechanism behind CISS remains elusive. This study reports spin‐selective electron transport through single helical aromatic hydrocarbons that are sublimed in vacuo onto ferromagnetic cobalt surfaces and examined with spin‐polarized scanning tunneling microscopy (SP‐STM) at a temperature of 5 K. Direct comparison of two enantiomers under otherwise identical conditions revealed magnetochiral conductance asymmetries of up to 50% when either the molecular handedness is exchanged or the magnetization direction of the STM tip or Co substrate is reversed. Importantly, the results rule out electron–phonon coupling and ensemble effects as primary mechanisms responsible for CISS.

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Electronic transport through single polyalanine molecules

Cited by 6 publications

References 29 publications

Cooperative effect of electrons spin polarization in a hybrid nanostructure of a magnetic thin film with adsorbed chiral molecules studied with non-spin-polarized scanning tunneling microscopy

Cooperative effect of electrons spin polarization in a hybrid nanostructure of a magnetic thin film with adsorbed chiral molecules studied with non-spin-polarized scanning tunneling microscopy

Cooperative Effect of Electron Spin Polarization in Chiral Molecules Studied with Non-Spin-Polarized Scanning Tunneling Microscopy

Spin‐Selective Electron Transport Through Single Chiral Molecules

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