Enantiomer-Selective Magnetoresistance in Chiral Gold Nanocrystals by Magnetic Control of Surface Potentials

TL;DR

This study discovers an enantiomer-specific magnetoresistance effect in chiral gold nanocrystals, where magnetic fields modulate resistance based on nanocrystal chirality, with potential applications in nanoelectronics and catalysis.

Contribution

The paper introduces a novel chirality-dependent magnetoresistance phenomenon in gold nanocrystals, controlled by magnetic fields and surface chemistry, expanding understanding of chiral nanomaterials.

Findings

Magnetic field reversibly modulates resistance in enantiomer-specific manner.

Surface chemistry tuning alters magnetoresistance magnitude and sign.

Effect observed in single nanocrystals and thin film devices.

Abstract

Chiral nanomaterials offer intriguing possibilities for novel electronic and chemical applications. Here, we report the discovery of an enantiomer-selective magnetoresistance effect in chiral gold nanocrystals. Based on precise control of nanocrystal chiral morphology using amino acid-directed synthesis, we demonstrate that an external magnetic field can dramatically modulate resistance in an enantiomer-specific manner. For a given enantiomer, a magnetic field in one direction alters the resistance by dozens of times, while the opposite field direction leaves it unchanged. This asymmetric response reverses for the opposite enantiomer and are reproduced in both single nanocrystals by conduction atomic force microscopy and nanocrystal thin films in solid state devices. We attribute this phenomenon to a chirality-driven charge pumping effect, where the interplay between the chiral morphology and the magnetic field selectively modifies the surface potential. The magnitude and sign of the magnetoresistance can be further tuned by the surface chemistry of the nanocrystal, as demonstrated through sulfide treatment. Our findings reveal a new form of chirality-dependent magnetoresistance, distinct from previously known effects such as chirality-induced spin selectivity and electric magnetochiral anisotropy. The ability to remotely control surface potentials of chiral nanostructures using magnetic fields could enable novel approaches in catalysis, drug delivery, and nanoelectronics.