Magnetic Field Enhanced Charge Conduction in Paramagnetic Nickel (II)-Cysteine Heterostructures

Abstract

A chiral ligand as a symmetry-breaking reagent can induce chirality in many achiral objects including inorganic heterostructures for probing organic-inorganic interfaces, chiroptical, chirality-induced spin-selectivity, and magneto-electrochemical phenomena. Chirality-induced paramagnetic heterostructures have not been explored in magneto-electrochemical and energy applications. We demonstrate the ability of L- and D-Cysteines to transfer chirality in achiral and paramagnetic nickel (II) heterostructures. A red shift in the circular dichroism spectrum of L and D-Cys-Ni (II) heterostructures compared to free L or D-Cys, a clear induction of chirality in paramagnetic nickel, a signature of chiroptical phenomena. The assemblies are exploited in two-terminal electronic devices that reveal nearly 50% enhancement of electrical current in the presence of an external magnetic field of 350 mT within a DC potential range of ±0.8 V. The chiral materials show nearly 58-85% enhanced Faradaic current in response to an external magnetic field of 350 mT placed underneath the L- and D-Cys-Ni (II) modified working electrodes in an electrochemical cell. Such enhancement in either the solid-state or magneto-electrochemical effect was observed due to the presence of paramagnetic Ni(II) ions that experienced a magnetic field which reduces the charge transfer resistance. A chiral potential and spin-orbit coupling in chiral heterostructures significantly contribute to spin-momentum that enhances charge conduction. The work highlights the importance of surface engineering in chirality transfer, which is sensitive to electrical conductivity and an external magnetic field.