Modeling spin selectivity in charge transfer across the DNA/Gold interface

2021

Nano Lett.

100

Chiral induced spin selectivity is a phenomenon that has been attributed to chirality, spin–orbit interactions, and nonequilibrium conditions, while the role of electron exchange and correlations have been investigated only marginally until very recently. However, as recent experiments show that chiral molecules acquire a finite spin-polarization merely by being in contact with a metallic surface, these results suggest that electron correlations play a more crucial role for the emergence of the phenomenon than previously thought. Here, it is demonstrated that molecular vibrations give rise to molecular charge redistribution and accompany spin-polarization when coupling a chiral molecule to a nonmagnetic metal. The presented theory opens up new routes to construct a comprehensive picture of enantiomer separation.

mentioning

confidence: 95%

mentioning

confidence: 99%

Charge Redistribution and Spin Polarization Driven by Correlation Induced Electron Exchange in Chiral Molecules

2021

Nano Lett.

100

“…On the theoretical side, an enormous effort has been devoted to achieve attractable model descriptions which enable reproduction of the experimental results, in terms of experimentally viable parameters, as well as to generate a sound comprehension of chirality induced spin selectivity. Different approaches can be categorized into hydro-dynamical, or, continuum models [14][15][16][17][18][19][20][21][22], tight-binding descriptions [23][24][25][26][27][28], and ab initio simulations using, for example, density functional theory [29][30][31].…”

mentioning

confidence: 99%

Chirality-Induced Spin Selectivity: The Role of Electron Correlations

2019

J. Phys. Chem. Lett.

105

118

Chirality induced spin selectivity, discovered about two decades ago in helical molecules, is a non-equilibrium effect that emerges from the interplay between geometrical helicity and spin-orbit interactions. Several model Hamiltonians building on this interplay have been proposed and while these can yield spin-polarized transport properties that agrees with experimental observations, they simultaneously depend on unrealistic values of the spin-orbit interaction parameters. It is likely, however, that a common deficit originates from the fact that all these models are uncorrelated, or, single-electron theories. Therefore, chirality induced spin selectivity is, here, addressed using a many-body approach, which allows for non-equilibrium conditions and a systematic treatment of the correlated state. The intrinsic molecular spin-polarization increases by two orders of magnitudes, or more, compared to the corresponding result in the uncorrelated model. In addition, the electronic structure responds to varying external magnetic conditions which, therefore, enables comparisons of the currents provided for different spin-polarizations in one of the (or both) leads between which the molecule is mounted. Using experimentally feasible parameters and room temperature, the obtained normalized difference between such currents may be as large as 5 -10 % for short molecular chains, clearly suggesting the vital importance of including electron correlations when searching for explanations of the phenomenon.

“…3−28 Despite the existence of non-equilibrium conditions, which define the measurements, for instance, light exposure, 1,2,31−36 local probing techniques, 37−40 transport, 38,41,42 and different types of Hall measurements, 32,33,43−45 many theoretical accounts of the effect are based on the transmission properties of chiral molecules embedded in a given environment. [3][4][5][6][7][8][10][11][12][13][15][16][17]19,20 While the transmission pertains to the linear response regime, hence, the ground state properties of the molecule, it is also often typically the result of a single-particle description that under stationary conditions cannot account for the excited state properties that underlie spin selectivity in chiral molecules.…”

mentioning

confidence: 99%

Charge and Spin Dynamics and Enantioselectivity in Chiral Molecules

2022

J. Phys. Chem. Lett.

Charge and spin dynamics are addressed in chiral molecules immediately after their instantaneous coupling to an external metallic reservoir. This work describes how a spin polarization is induced in the chiral structure as a response to the charge dynamics. The dynamics indicate that chiral induced spin selectivity is an excited state phenomenon that in the transient regime can be partly captured using a simplistic single-particle description but in the stationary limit definitively shows that electron correlations, e.g., electron−vibration interactions, crucially contribute to sustain an intrinsic spin anisotropy that can lead to a nonvanishing spin selectivity. The dynamics, moreover, provide insight into enantiomer separation, due to different acquired spin polarizations.