Chirality Induced Spin Selectivity -- The Role of Electron Correlations

TL;DR

This paper uses a many-body approach to study chirality-induced spin selectivity, revealing that electron correlations significantly enhance spin polarization and align theoretical models more closely with experimental results.

Contribution

It introduces a correlated many-body model for CISS, showing increased spin polarization and better agreement with experiments compared to uncorrelated models.

Findings

Electron correlations increase spin polarization by over two orders of magnitude.

The electronic structure varies with external magnetic fields, affecting spin-polarized currents.

Normalized current differences can reach 5-10% at room temperature for short molecules.

Abstract

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.