CISS effect: Magnetocurrent-voltage characteristics with Coulomb interactions. II

Area of Science:

• Condensed matter physics
• Molecular electronics
• Spintronics

Background:

• Chirality-induced spin selectivity (CISS) is a phenomenon where chiral molecules induce spin polarization in charge transport.
• Magnetocurrent, a key CISS manifestation, is defined as the change in current due to altered magnetization in a device.
• Experimental observations of magnetocurrent in chiral molecular systems often show an odd voltage dependence, contrasting with some theoretical predictions.

Purpose of the Study:

• To analytically investigate the voltage dependence of magnetocurrent in bipartite-chiral structures.
• To clarify the role of Coulomb interactions and lead symmetries in magnetocurrent generation.
• To reconcile theoretical predictions with experimental findings regarding magnetocurrent asymmetry.

Main Methods:

• Analytical derivation of magnetocurrent in bipartite-chiral systems.
• Utilizing Green's function formalism to analyze electron transport.
• Employing wide-band and semi-infinite lead approximations.
• Numerical simulations to validate analytical results.

Main Results:

• Magnetocurrent mediated by Coulomb interactions is analytically shown to be exactly even in the wide band limit.
• Magnetocurrent is analytically shown to be exactly odd for semi-infinite leads.
• The bipartite lattice symmetry of the Green's function dictates the parity of the magnetocurrent.
• Numerical results confirm the analytical predictions for both even and odd magnetocurrent behavior.

Conclusions:

• The symmetry of the leads and the nature of interactions significantly influence the magnetocurrent's voltage dependence.
• Coulomb interactions in bipartite-chiral systems can lead to both even and odd magnetocurrents depending on the lead characteristics.
• This work provides a theoretical framework to understand the observed magnetocurrent asymmetry in molecular spintronic devices.