Tuning spin filtering by anchoring groups in benzene derivative molecular junctions

Area of Science:

• Molecular spintronics
• Quantum transport phenomena
• Materials science

Background:

• Controlling charge transport and spin polarization in single-molecule junctions is crucial for molecular spintronics.
• The choice of anchoring groups significantly impacts the electronic properties of molecular junctions.

Purpose of the Study:

• To investigate the effect of different anchoring groups on spin-polarized electron transport across single benzene derivatives.
• To explore the potential for high spin polarization and magnetoresistance in molecular spintronics devices.

Main Methods:

• Ab initio calculations were employed to simulate electron transport.
• Six different anchoring groups (S, CH3S, COOH, CNH2NH, NC, and NO2) attached to Ni(111) electrodes were studied.
• Analysis involved examining molecule-electrode coupling, conductance, and spin polarization.

Main Results:

• Anchoring groups significantly modify molecule-electrode coupling, conductance, and spin polarization.
• NO2 terminations demonstrated high spin polarization (>80%) and giant magnetoresistance (>140%), with further enhancement under small voltages.
• S and CH3S groups showed low spin polarization, while COOH and CNH2NH groups exhibited intermediate values.

Conclusions:

• Anchoring group selection is critical for tuning spin polarization and conductance in molecular junctions.
• NO2-terminated benzene derivatives show promise for high-performance spintronics applications.
• Orbital symmetry, hybridization, and frontier orbital localization explain the observed transport properties.