# Tuning spin filtering by anchoring groups in benzene derivative molecular junctions

## TL;DR

This study uses ab initio calculations to demonstrate how different anchoring groups in benzene derivatives influence spin polarization and conductance in molecular junctions, offering insights for designing advanced spintronic devices.

## Contribution

It systematically analyzes the effect of various anchoring groups on spin transport properties in benzene-based molecular junctions, revealing how to optimize spin polarization and magnetoresistance.

## Key findings

- NO2 anchoring groups achieve >80% spin polarization and >140% magnetoresistance.
- Spin polarization can be enhanced up to 90% with small voltages.
- Different anchoring groups significantly alter conductance and spin filtering efficiency.

## Abstract

One of the important issues of molecular spintronics is the control and manipulation of charge transport and, in particular, its spin polarization through single-molecule junctions. Using $ab$ $initio$ calculations, we explore spin-polarized electron transport across single benzene derivatives attached with six different anchoring groups (S, CH$_3$S, COOH, CNH$_2$NH, NC and NO$_2$) to Ni(111) electrodes. We find that molecule-electrode coupling, conductance and spin polarization (SP) of electric current can be modified significantly by anchoring groups. In particular, a high spin polarization (SP $>$ 80%) and a giant magnetoresistance (MR $>$ 140%) can be achieved for NO$_2$ terminations and, more interestingly, SP can be further enhanced (up to 90%) by a small voltage. The S and CH$_3$S systems, on the contrary, exhibit rather low SP while intermediate values are found for COOH and CNH$_2$NH groups. The results are analyzed in detail and explained by orbital symmetry arguments, hybridization and spatial localization of frontier molecular orbitals. We hope that our comparative and systematic studies will provide valuable quantitative information for future experimental measurements on that kind of systems and will be useful for designing high-performance spintronics devices.