Spin Specific Electron Conduction through DNA Oligomers

Abstract

Spin-based properties, applications, and devices are commonly related to magnetic effects and to magnetic materials. Most of the development in spintronics is currently based on inorganic materials. Despite the fact that the magnetoresistance effect has been observed in organic materials, until now spin selectivity of organic based spintronics devices originated from an inorganic ferromagnetic electrode and was not determined by the organic molecules themselves. Here we show that conduction through double-stranded DNA oligomers is spin selective, demonstrating a true organic spin filter. The selectivity exceeds that of any known system at room temperature. The spin dependent resistivity indicates that the effect cannot result solely from the atomic spin-orbit coupling and must relate to a special property resulting from the chirality symmetry. The results may reflect on the importance of spin in determining electron transfer rates through biological systems.

Spin-dependent electron transport in protein-like single-helical molecules

“…These results are in excellent agreement with recent experiments [Mishra D, et S pintronics is a multidisciplinary field that manipulates the electron spin transport in solid-state systems and has been receiving much attention among the physics, chemistry, and biology communities (1)(2)(3)(4). Recent experiments have made significant progress in this research field, finding that doublestranded DNA (dsDNA) molecules are highly efficient spin filters (5)(6)(7). This chiral-induced spin selectivity (CISS) is surprising because the DNA molecules are nonmagnetic and their spin-orbit couplings (SOCs) are small.…”

Structure dependent spin selectivity in electron transport through oligopeptides

“…9 The effect was explained by the fact that a longer tunneling barrier is more efficient in reducing the tunneling probability of the "unfavored spin" as compared to the "favored" one. As seen in Figure 3(C), whereas the efficiency of spin filtering for the two species is quite similar at the lowest forces, it drops much more dramatically for Al5 at higher loading forces.…”

“…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. 23 The sign of the favored spin can be reversed by light, as was shown for an oligopeptide-CdSe hybrid 22 and also by lowering the temperature, which causes cold denaturation of the peptide-made monolayers, as seen in an oligopeptide-CdSe hybrid studied in the Hall configuration.…”

“…23 It was also found that for given oligomers (DNA or peptides) longer molecules lead to better spin filtering. 8,9,13 Thus, there is abundant experimental evidence that the CISS effect depends on the structural parameters of the chiral molecules.…”

Spin filtering in all-electrical three-terminal interferometers

“…(24) and (25) (27) achieved in a symmetric interferometer are equal in magnitude and of opposite signs. 69 However, asn 1 =n 2 , the total polarization (11) does not vanish even in the symmetric case.…”