Magnetoresistance and Spin-Filtering Efficiency of Dna-Sandwiched Ferromagnetic Nanostructures

Ravi, S.; Sowmiya, P.; Karthikeyan, A.

doi:10.1142/s2010324713500033

Cited by 25 publications

(16 citation statements)

References 14 publications

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“…The CISS effect relates to the ability of chiral molecules to transmit electrons in a spin-selective manner, hence the molecules act as spin filters. 6,7 Several chiral molecular species including DNA, [8][9][10][11][12] oligopeptides, [13][14][15] bacteriorhodopsin (bR), 16,17 a chiral conductive polymer, 18 1, 2-diphenyl-1,2-ethanediol (DPED), 19 helicenes, 20 and recently chiral CdSe quantum dots 21 have demonstrated efficient spin filtering. The spin filtering ability can be tuned by various means, for example, by varying the length of the chiral molecule, 8,9,13 by exposure to light, 22 or by varying the temperature.…”

Section: Introductionmentioning

confidence: 99%

Structure dependent spin selectivity in electron transport through oligopeptides

Kiran

Cohen

Naaman

2016

The Journal of Chemical Physics

108

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The chiral-induced spin selectivity (CISS) effect entails spin-selective electron transmission through chiral molecules. In the present study, the spin filtering ability of chiral, helical oligopeptide monolayers of two different lengths is demonstrated using magnetic conductive probe atomic force microscopy. Spin-specific nanoscale electron transport studies elucidate that the spin polarization is higher for 14-mer oligopeptides than that of the 10-mer. We also show that the spin filtering ability can be tuned by changing the tip-loading force applied on the molecules. The spin selectivity decreases with increasing applied force, an effect attributed to the increased ratio of radius to pitch of the helix upon compression and increased tilt angles between the molecular axis and the surface normal. The method applied here provides new insights into the parameters controlling the CISS effect. C 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license

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Section: Introductionmentioning

confidence: 99%

Structure dependent spin selectivity in electron transport through oligopeptides

Kiran

Cohen

Naaman

2016

The Journal of Chemical Physics

108

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confidence: 95%

“…This effective field stabilizes one spin orientation of the electrons over the other and gives rise to a spin-dependent transmission (11). Since its discovery, the effect has been observed experimentally and verified in different systems (12)(13)(14)(15)(16)(17)(18).In the first part of this manuscript, we describe how the spin polarization in monolayers of chiral molecules was measured, and in the second part, we present calculations on model systems and discuss how this phenomenon introduces considerations for describing the interaction between chiral molecules. …”

mentioning

confidence: 97%

Chirality-induced spin polarization places symmetry constraints on biomolecular interactions

Kumar

Capua

Kesharwani

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

185

247

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Noncovalent interactions between molecules are key for many biological processes. Necessarily, when molecules interact, the electronic charge in each of them is redistributed. Here, we show experimentally that, in chiral molecules, charge redistribution is accompanied by spin polarization. We describe how this spin polarization adds an enantioselective term to the forces, so that homochiral interaction energies differ from heterochiral ones. The spin polarization was measured by using a modified Hall effect device. An electric field that is applied along the molecules causes charge redistribution, and for chiral molecules, a Hall voltage is measured that indicates the spin polarization. Based on this observation, we conjecture that the spin polarization enforces symmetry constraints on the biorecognition process between two chiral molecules, and we describe how these constraints can lead to selectivity in the interaction between enantiomers based on their handedness. Model quantum chemistry calculations that rigorously enforce these constraints show that the interaction energy for methyl groups on homochiral molecules differs significantly from that found for heterochiral molecules at van der Waals contact and shorter (i.e., ∼0.5 kcal/mol at 0.26 nm).spin | chirality | enantioselectivity | biorecognition | exchange interaction T he wealth of information on protein structure has led to a much better understanding of the relation between structure and function in biomolecular processes and biological machines (1); however, basic phenomena remain unexplained in terms of structure-function relationships. Biorecognition, which is based on noncovalent interactions between molecules, retains mysteries, and its calculation evades first principles theory (2, 3). This failure suggests that some essential features are not included in our current description of these interactions (4,5). In this study, we show that charge polarization, which occurs in any biorecognition event, is accompanied by spin polarization for chiral molecules, an effect that is missing in most treatments. The subsequent magnetic interaction energies are small and therefore, play no significant role in the interactions; however, the spin polarization constrains the symmetry of the wave function(s) involved with the intermolecular interaction, so that significant differences in energy emerge for interactions between molecules of the same chirality and those of opposite chirality. Thus, this phenomenon may impact quantitative modeling of biorecognition events and contribute to our understanding of enantiorecognition in nature (6).Nucleotides, amino acids, and sugars are chiral; namely, they do not possess mirror plane symmetry but have symmetry like a "hand" (cheir in Greek). Force field models for the interaction between biomolecules do not account for spin polarization or include terms with chiral symmetry. Noncovalent interactions between biomolecules are commonly described classically by way of force fields, which are constructed from their geometrie...

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“…Considering the bare p orbitals on the bases, the possible SO matrix elements between these orbitals are Chiral Induced Spin Selectivity (CISS) consists of the strong spin polarization of electrons when they are transmitted through a chiral structure. The CISS effect has been measured in a great variety of chiral molecular structures including single molecules of DNA, [8][9][10] Photosystem I, [11] self-assembled monolayers of DNA, chiral oligopeptides [12,13] and helicenes. [14] As these molecular systems lack strong exchange interactions and magnetic centers, it was first proposed that the spin-active ingredients to the photo-electron spin polarization setup [8] was the SO coupling [15] in addition to the chiral potential.…”

Section: Analytical Slater-koster Model For Double-stranded Dnamentioning

confidence: 99%

“…As the bases rotate along the helix we must consider that the orbitals do not have the same absolute orientation at each site. [28] Using X, Y ˆ, Ẑ as the basis fixed in space, we define the unit vectors n ( µ  ) in the direction the orbital µ j living on the helix as (10) with φ ı = (ı -1)∆φ, where ı = 1...N and N is the total number of sites on helix. If the orbitals µ ı are located in R ı and the orbitals µ' are in R j , overlap between the orbitals at ı and j sites are given by…”

Section: Stretching Effects On So Couplingmentioning

confidence: 99%

Spin-orbit Coupling Modulation in DNA by Mechanical Deformations

Varela

Mújica²,

Medina

2018

Chimia

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We consider molecular straining as a probe to understand the mobility and spin active features of complex molecules. The strength of the spin-orbit interaction relevant to transport in a low dimensional structure depends critically on the relative geometrical arrangement of current-carrying orbitals. Understanding the origin of the enhanced spin-orbit interaction in chiral systems is crucial to be able to control the spin selectivity observed in the experiments, which is a hallmark of the Chiral-Induced Selectivity Effect (CISS). Recent tight-binding orbital models for spin transport in DNA-like molecules, have surmised that the band spin-orbit (SO) coupling arises from the particular angular relations between orbitals of neighboring bases on the helical chain. Such arrangements could be probed by straining the molecule in a conductive probe AFM/Break junction type setup, as was recently reported by Kiran, Cohen and Naaman. Here we report strain-dependent kinetic and SO coupling when a double-strand DNA model is compressed or stretched in two experimentally feasible setups with peculiar deformation properties. We find that the mobility and the SO coupling can be tuned appreciably by strain, and the analytical model bears out the qualitative trends of the experiments.

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Magnetoresistance and Spin-Filtering Efficiency of Dna-Sandwiched Ferromagnetic Nanostructures

Cited by 25 publications

References 14 publications

Structure dependent spin selectivity in electron transport through oligopeptides

Structure dependent spin selectivity in electron transport through oligopeptides

Chirality-induced spin polarization places symmetry constraints on biomolecular interactions

Spin-orbit Coupling Modulation in DNA by Mechanical Deformations

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